Create your own at NAG, the Net Art Generator
They say......"the net.art generator creates images. The resulting image emerges as a collage of a number of images which have been collected on the WWW in relation to the 'title' you have chosen. The original material is processed in 12-14 randomly chosen and combined steps."
And in the same vein, I discovered another 'randomiser' that came in VERY handy when I needed a grungy background image for a poster in a hurry last week.....this one uses type to wave it's magic wand........
Try TypoGenerator next time you're short on inspiration.....it worked for me!