When I was in Georgia, I used to leave a $1.00 scratch off lotto ticket. I felt like that was a good trade item. Relatively cheap unless you're doing a lot of caches in a little time. On my very first FTF, I got a geocaching hat with a red bow around it. I was tickled to death, you'd a thought I won the Price is Right or something. Any geocaching item w/the logo is good also. I have taken to leaving lightsticks in caches also. My personal feeling is to leave as well as you can afford, I think if the cache is hidden well enough, muggles shouldn't be a problem.