Pink Floyd is good, Primus is unique and worth a listen, Tool, A Perfect Circle, PHISH (No one else seemed to have mentioned this one), If you like Flaming Lips then check out Modest Mouse, they have a similiar goofy/quirky feel to them, If you like Primus and Phish, there's a band which is pretty much the equivalent of the two combined called Oysterhead, Bela Fleck and The Flecktones are a good instrumental band, Beck, Cake, The Strokes if you want some lo-fi garage-style rock, and They Might Be Giants, if you're in the mood for something goofy and light. I'm just throwing out stuff that I love.