Being that its "hot" why not a Jello salad, different colors and you cut them in pieces( red, whiote,blue?) for the fourth of July? and add some whipped cream to the pieces, and I think about 3 boxes of the stuff should do it, that should serve 12, well if you get the bigger boxes anyway.
also why not a veggie tray.
celery, broccoli, cauliflower, pickles, peanuts? awww cheese too.
oh this too, INEXPENSIVE!!
I have small group this weekend, so keep the ideas coming...