I'm currently working on Haskell. Others on the short list would be Go and Clay (since it sounds nice to have a systems language other than C, and they look int

I'm currently working on Haskell. Others on the short list would be Go and Clay (since it sounds nice to have a systems language other than C, and they look interesting), OCaml (to go with Types and Programming Languages), and Objective-C (since I'm primarily on OS X). It probably wouldn't be hard to talk me into working on a Lisp either.