I’ve look at a lot of clip art and vector art via Google image search in the process of creating my Conspiracy! evidence cards. It’s a way to crank out quick prototype cards without fussing with original art (or artless cards, which are no fun). If the game ends up being good enough to publish, I’ll worry about generating original art at that time. Until then, I’ll use anything I can steal off the interwebs for free.
As I said, I look at a lot of clip art. That being said, I see a lot of … weird clip art.
Here, in place of anything thoughtful, are some of my favorites.