We made up snack size baggies with a card and marbles to leave in every cache we visit. The marbles were for the kids, card is just our geocaching avatar and geocache email address. Figured if newer caches want to email to learn more about caching (and get pointed to here) that's great. This isn't a "trade" item but just something extra to leave. If we do trade, we try for something geo related. Our best one was a good quality vinyl sticker for the car window with a geo logo. Unfortunately when we went to reorder, there is no trace of the company and they don't answer phone or email calls. Disappointing but might look for another source such as the main gc site.
Hadn't thought about cleaning out the junk in caches since we figured the cache owner had that responsibility. I do have quite a collection of small rubber amphibians in a dish on my kitchen sink. Try explaining that to visitors!
TwoMaineiacs / Anne and Joe