If you are looking for another language community to join, consider Haskell.
We are still pretty small, but the discussions on the list and IRC are always interesting and low-heat.
That, and Haskell is the opposite of Python in many ways. So (without applying too many prejudgements) it is likely to stretch your mind more than other languages might.
Personally, Python and Haskell are the languages that have had the most influence on my skills as a software developer. Although, I still haven't learned a lisp flavor, so it might be a little early to judge.
I'm not so much looking for another language, as a community that isn't a language. Or a pan-language community. To a degree "the free software community" might be that community. But I'm not sure what/where that community is. I think GNU used to be a community, but I'm not sure if it is anymore. That mission is either lost or satisfied.# Ian Bicking