I'd like to find useful (or at least new) stuff like mini first-aid kits, flashlights, geocaching pins, stickers, etc., or anything unusual and just plain cool. Basically anything that hasn't been beat to heck and looks ready for the trash would be an upgrade from what I've been finding; soggy band-aids, golf balls, a spider rings, rubber lizards.
I work for LEGO, and often leave BIONICLE, EXOFORCE, and the like, I've also left jewelry, candles, foreign coins, batteries, etc. But with the junk I've been finding, I often TNLN. As much as I enjoy the hunt, it would be nice to have a keepsake from each cache I find.