Here's three I hope will stick around.
Pretzel Buns - any burger or sandwich seems improved with one of these.
Chicken Salad - we had a restaurant open nearby that serves 16 versions of chicken salad. I like that, although I don't need to see 4 competitors open up on the same block.
Lactose free foods - bravo to Breyers for bringing out at least a couple flavors of lactose free ice cream. I wish the Lactaid yogurt and cottage cheese had caught on and stuck here.