With such a huge array of potential knowledge, how do we go about capturing it, becoming proficient in it, and putting it to good use? Every programmer has their own preferred method of gaining new programming knowledge, and different things work better for different people, so I'm not going to push one particular method. Well, not too much anyway. Instead, I'm going to attempt to show the plethora of options available for improving your 1337 programming skillz. Once again, this is probably not a complete list.
The Old Fashioned Way
You could start off learning a broad spectrum of software engineering knowledge by going to college. Coupling a Computer Science degree with a Mathematics degree will cover a lot of ground in four or five years. You can also continue on for a Masters or PhD to go deeper and deeper into the fields that you're interested in. College can be great for providing direction and focus in learning, if you have the motivation and don't let too much partying go to your head. Being surrounded by a large group of other smart, motivated people can be encouraging and stimulating. College courses also have the advantage of a fairly well-packaged set of resources and a discernible learning path for the subject areas you decide to pursue.
There are trade-offs, though. College programs are often short on experience, and unless you go for internships, (recommended) you won't have a very good idea of how software engineering is done in the real world. It's also expensive, both in time and money, and it isn't for everyone. Even for those that do go to college, and go on to Master's and PhD programs, it will (or at least should) eventually end. Then staying up on current technology becomes an individual enterprise. Even right out of college, grads don't know everything, so what else can we do to keep learning?
There's always books ... lots of books. If you haven't noticed, this is my currently preferred and primary method of learning more about pretty much anything. I love books. They give an in depth treatment of any given subject in a nice, manageable package that can be easily reviewed, referenced, and now with ebooks, searched for vast quantities of information. There are books on nearly any subject you can think of, and I've had good luck finding high quality books ever since Amazon reviews became ubiquitous.
Even in college I quite often relied on the textbooks as much or more than the professors, but books can't teach you everything. They are an individual pastime that is distinctly lacking in connections to the programming community as well as being short on giving you real-world experience. Beyond that, most programming books can quickly become obsolete as the software they cover continues its eternal progression, so books at least need to be supplemented with more up-to-date and connected ways of learning.
The Newfangled Way
To get connected with a programming community and learn new things at the same time, you can participate in online communities like Hacker News, reddit.com/r/programming, IRC, and LinkedIn groups. You'll be aware of current trends, see new developments as they happen, and be able to join discussions and debates with other programmers. You'll also get a better idea of who's who in the programming world and be able to see first hand how trends are developed and promoted.
You can also participate in communities that focus on teaching and learning in a more permanent format, like Stackoverflow.com or Quora.com. Like most other online communities, they have a gamification aspect where you gain reputation as you ask good questions and provide good answers. But unlike HN, reddit, etc., the questions and answers are easily searchable and available to newcomers so that your contributions will potentially have a larger impact over time, and you can find information on specific topics that was already covered months or years in the past.
Once you've spent some time in some of these communities, you'll likely find some interesting blogs to follow. That's another great way to learn more about different areas of programming, and if you read some blogs from their early beginnings to the present, you'll be able to see how other programmers have developed throughout their careers.
You may even get the urge to start your own blog, and put your own experiences online. Then, instead of only receiving new knowledge, you can develop an ability to teach others what you know. In addition to contributing more to the community, you also gain a much deeper understanding of the topics you're trying to write about. Knowing something is one thing, doing it is another, and teaching it is still another. To effectively teach anything, you have to organize your thoughts in new ways and spend more time wringing out the misconceptions and uncertainty that you may have on the subject. It's harder than you think, and you'd be surprised how much you don't know about things that you thought you could do in your sleep.
However, reading and writing about software engineering can only get you so far. At some point you're going to want to get your hands dirty and do some real programming. Well, there's plenty of resources for that, too.
The Hands-On Way
To get some real programming practice in, you could go to some of the excellent programming puzzle sites for ideas. There's sites like Project Euler, Programming Praxis, Prolog Problems, Code Golf on StackExchange, Python Challenge, and Ruby Quiz to name just a few. Solving programming puzzles is a great way to practice and get better at the fundamentals of programming, or to get ideas for small exercises that you can do to get more familiar with a new language you're learning.
Speaking of new languages, learning another language is an excellent way to learn a lot about new areas of software engineering, especially if that language lives primarily in an environment that you're not familiar with. To learn C#, you'll have to learn a lot about the Windows programming environment. Learning Objective-C will lead you into MacOS and iOS programming. Learning Prolog would be a useless undertaking without also learning a lot about AI. Erlang will provide the impetus to learn more about concurrency and parallel computing. And Lisp will most likely bring you up close and personal with Emacs.
If you're starting out with a new language, there are also a number of online resources out there to help you with the basics, especially if you're fairly new to programming and it's a popular language. Sites like RubyMonk.com, Scratch.mit.edu, and W3Schools.com can get you up and running with a new language through a fun, interactive experience.
While solving puzzles and learning new languages will help you a lot, we still haven't covered great ways to get real-world experience doing larger projects. For that experience, one of the best ways to learn outside of having a job in software engineering, is to contribute to an open source project. Joining an open source project will not only help you learn how to work within a larger software team on a more significant project, but you will also be making a meaningful contribution to the community by helping out on a software project that may be used by thousands of people.
Working on open source software will also give you a better idea of how to write good, high quality code, at least if you happen to be reading good, high quality code. But there's a good chance that you will be, especially if you're looking at the standard libraries for your favorite language or the more popular frameworks and projects on GitHub - the go-to site for finding good open source projects to contribute to.
If you don't want to join an already active project, you can always start one of your own. Coming up with an idea for a new software project and following it through design, development, and release is a great way to develop your programming knowledge, and there are plenty of important problems out there yet to be solved with a good piece of software. You're guaranteed to learn a lot, and the project may even take on a life of its own and take you to places you never imagined you could go.
These projects can range from web design to mobile apps, games, and even embedded products. No matter what kind of programming you want to learn, there's an affordable way to do what you want to do. The barriers to entry have never been lower. Whether its free web hosting at sites like Heroku, or inexpensive embedded kits like Arduino, Raspberry Pi, and Tiva Launchpads, There are all kinds of interesting options for pursuing your DIY urges. I'm especially interested in checking out Make: magazine for all kinds of embedded software project ideas, although I'm afraid I wouldn't be able to resist overdoing it and it would consume all of my time. Maybe I need to wait until my kids are old enough to enjoy those projects with me, and we can learn together. It shouldn't be long now.
Oh, Is That All?
With so many options available, how does one choose what to do? Like the options for what to learn to improve as a software engineer, the options for how to learn it can be overwhelming. It is largely a personal choice, and what works well for some people will be tedious or ineffective for others. For example, I am quite happy reading books and working out programming puzzles, but I can't stand watching instructional videos or screen casts. Another programmer may have trouble concentrating on a book but gets a lot out of video lectures or debating in online forums. The point is to figure out how you are most effective at learning and focus on that. Make the most of the time you have.
I have one piece of advice, though. Try to find a good balance between studying, practicing, and participating. If you spend too much time on any one of those things, it can start to become an end unto itself. That's okay if your goal is to read tons of books or build up a lot of reputation on Hacker News or solve as many puzzles as you can. If you enjoy what you're doing, that's great, but be honest with yourself about what your goals are. If your end goal is to improve as a programmer, or more specifically, learn what you need to learn to accomplish whatever it is you want to do with programming, you're going to make faster progress if you strike the right balance. I'd love to tell you what that is, but you're going to have to discover it on your own.