Podiobooks.com- Podcast audiobooks. Sounds odd, but they're great for people (like me) for whom drawing is a mindless kind of activity during which you can be listening to and thinking about something else.
Screentones- Free digital screentones. I use a lot of these for DC.
Posemaniacs.com- 3D pose references. Very useful.
Gendou's Anime Music- Fot those of us who are addicted to those crazy anime themes.
Dafont.com- Neat downloadable fonts.
You Are A...- Just click it. You'll have fun XD.
The Phoenixian Book of Creatures- Detailed list of mythological creatures and info about them. Good for monster lovers like myself.
20000-names.com- If you ever need a character name, look here XD
Evil Overlord List- If you've never read this, do it now XD.
Seventh Sanctum- All sorts of generators. Good for inspiration, or just a laugh.
...I'll add more to these later.