On my most recent dive (Blue Heron Bridge, Florida) I picked up some wads of fishing line and hooks while I was diving and carried them around in my thigh pocket for later disposal. I left a corroding duracell battery, though, because I had nothing to put it in that wouldn't contaminate my gear and while I want to help clean up clearly corroded batteries can be seriously nasty to handle.
I wish I had a plastic baggie or something I could have put the battery in but I'm not sure it would have helped.
Anyway, how much do you collect/clean as you're diving and what do you "leave for more prepared cleaners" like the battery I mentioned above? Do you carry anything special for cleaning up on routine dives or just on "clean up days"?
If a battery is obviously corroded (bulging, split open, etc), I'll put it in my pocket. These small disposable batteries have a small amount of caustic soda inside. Once submersed in sea water, the corrosive material is leached out and the contents become the same pH as the surrounding sea water.
I retrieve fishing line, plastic bags, nylon rope, lost anchors, and occasionally beach and deck furniture.