Okay, first off, for everyone who's sitting there listening to their playlist for the 100th time in a row (like me) and is starting to kinda want something new, you might want to check out Pandora. It's an internet radio station that takes the kind of music you listen to and compiles a list of similar music. You can rate the songs they give you, to help them further refine the search. 'Tis great.
For those of you who like a little humor with your music, you should definately head over to SongsToWearPantsTo.com. This guy is a genius. He takes your requests and turns them into songs (although not all of them make it. The only way to guarantee he'll make yours is to make a paid request). And because I am the wonderfully nice person I am, I've got a few of his songs up for download. Check 'em out.
Well, I know there's gotta be at least a few of you who are just looking for something to do, so if you're in a quiz taking mood some good sites are: Quizilla and I-Am-Bored.com
If you're looking for some good forums/message boards, the-N and the SSF (Skye Sweetnam Forums. One of the best artist forums I've ever seen. The boardies or "soldiers" there are super nice.) are some great places to check out.
Napoleode (feat. Eko) - Songstowearpantsto.com
Megabytes and Gigabytes Freestyle - Songstowearpantsto.com
The Izzy and Taco Show - Songstowearpantsto.com
Underage Stalkers - Songstowearpantsto.com (my personal fave.)