Old fashioned toothpaste - not the gel kind - will take the sting and itch out of insect stings, and a dab on a fever blister will dry one up pretty quick too. I imagine it would work just as well on poison ivy and the like, too.

Also cortizone ointment rather than benadryl, is much more effective at taking the itch out of bug bites, since it is a steroid and benadryl isn't.