You can't miss: FFFFound

Yes, I did actually spell it right: 4 f's and an ound. ffffound. It's similar to ImageSpark (a great find from Sarah.) Basically, it's just a bunch of images meant to spark your creativity. I love it because it's not just magazine design or product design. It's all art-based, whether photographic, computer-generated or wet-brush. Have a look; here's one I like.