Well, I'd like to see more support of MicroPython on AVR, for starters - it already covers a bunch of platforms, but more hands seem welcome :)

If that's not your cup of tea, I'd say what I don't want is another IDE that forces me to have a JVM installed (I already do for Clojure, but sort of resent it) and ARM support (as a development platform, since I use an ODROID development board as a "desktop").