I too like to play with cookie flavors. I had found a 'thin mint' roll out recipe, which while 'ok', I knew I could do better. So I now use LiaLoa's chocolate roll out recipe and add 1/3 C. Thin Mint 'bits' finely chopped and 1/2 t. Creme de Menthe emulsion (or 1/4 t. peppermint extract would do the same thing). This cookie dough is addictive, and while I have 'trained' myself to not eat a lot of cookies now that I bake so much, these I have to decorate and bag FAST so I don't munch on them they are soooo good!
The down side to these additions is you sacrifice a really smooth top to you cookie, hey, I'm good with that. I also found an Oatmeal Raisin Roll Out Cookie recipe that is simply delish. A bit of work since I hand cut the raisins to be tiny, and chop the oatmeal in a blender to make it fine, but that is a really good cookie, but again, no smooth top for decorating!