I use it as a substitute for sour cream or heavy cream in things like mashed potatoes and sauces. Here's an example of a recipe where greek yogurt is used in the place of heavy cream to make a creamy tomato sauce for pasta. backtoherroots.com/2012/03/20/penne-rosa-w
Also this recipe for mashed potatoes is my go-to one now, and I use greek yogurt instead of the sour cream that's called for: www.skinnytaste.com/2008/03/garlic-mashed-
I've tried it as a sub for cream in more "watery" sauce like for a curry or for soups, but that didn't work out as well... it usually curdles.
I've not tried it, but I've heard it's excellent mixed with a ranch or onion seasoning packet to make a dip for veggies and chips.