Here are some of my favorite websites. Listed in no particular order.
This is where you can get one of the greatest media players around: XMPlay. It can play just about anything, including the tracked music on this website. It's free, extremely lightweight, easy to use, highly customizable, etc. The only downside is that there are no versions for Linux or Mac. :(
There is lots of other audio-related stuff, too, including BASS.DLL, which is what I used to make BGM.
This is the new home of Game Maker, one of the most powerful, easy-to-use, and fully-featured general-purpose computer game SDKs available for Windows.
Also, this new site has TONS of free games to download, all of which were made using Game Maker. Some of them are so good that they rival the games from professional companies.
Holy crap. It is absolutely mandatory that you at least have a rudimentary understanding of Homestar Runner, especially StrongBad Emails, if you are going to go anywhere in life. Sewiously.
This website has various tracking resources, including the excellent Modplug Tracker software for Windows. The original MPT is now a dead project, but the last working version of the software is still available on their site if you do a little work to search for it. It will work with Linux through Wine.
Here is another good module tracker. It is based on FastTrackerII, the famous tracker for DOS. It is fairly easy to use and has a very nice interface. It runs a little slow on some computers, but it has tons of excellent features, such as a tool for drawing waveforms by hand or generating them, which is great for chiptunes. Best of all, it runs on Windows, Mac, Linux, and a handful of other platforms.