If you're ever feeling a bit lost in the midst of an Internet search, fear not: Randall Munroe, the author of the Webcomic xkcd, has created a nifty map of the system to point you in the right direction.
OK, fine. It's not that kind of map. (It's missing the all-important "You are here" symbol, for example.) But it's an impressively elegant piece of work, accompanied by an interesting account of how he went about the mapping task.
Munroe, by the way, is a former NASA roboticist.