I like foreign coins as swag. They're handy to carry and interesting to just about everybody. A lot of the caches don't have much room in them but a few coins will go in with no problem. They are much more interesting to find than a couple of US pennies, nickles, and dimes which seem to be common in caches around here.
You can get foreign coins on ebay for pretty cheap. Even something as little as a quarter pound of world coins would have about 25 or 30 coins in it.
Most pathetic thing I have found in caches.. how about spent shotgun shells.