A few notes that I've found:
-I like "SystemPanel" a TON more than ATK. I urge people to check it out. Gives more information than you could ever want.
-Pandora in my tests consumed about 15% battery life per hour (over 3G and high quality)
-The default music player will use about 8% battery life per hour
-YouTube consumed about 50% battery life per hour over 3g.Has anybody else found something like that? To test I fired up the Conan O'Brien visits Google video that's like 50 minutes long.
These results did not use any sort of task killer.