T.H.
I pretty much just stock it up with a variety of pickles and olives. Sometimes I throw in some nuts or cheese cubes, but you can go for variety! Sweet pickles, dill pickles, bread and butter pickles, blue cheese stuffed olives, Greek olives, black olives, etc. Hot peppers and artichoke hearts were also good suggestions, but if you're having other trays, I'd do pickles, nuts, olives and cheese if you don't have someone doing that yet.