Mostly dynamic languages. I really like statically typed languages for certain tasks, but many times a dynamic language that gets out of your way can be quite liberating.  It takes a lot of trust compared to a language where your compiler is what you trust - and occasionally you spend a bit of extra time tracking down why things are in a state other than what you expect, but on the whole it takes the time from this is what I need to this is what I have down considerably.