Beside Snails and frogs, does anyone have crayfish, muessls, clams or anything else exotic in there ponds. I would like to put a few of those things into the pond i am building.

I don't know that they're exotic but they do have special needs. Crayfish are eaten by larger fish, raccoons, etc. but also themselves eat small fish and such. Freshwater mussels and clams gain their food by sifting the water column. If the pond is too clean, they starve. My ponds have fish, snails, frogs, and lots of various smaller animals (insects, worms, arachnids, etc.).