Haskell Activity
I'm relatively new to the Haskell community; before diving in this fall, I'd thought that it was probably a really innovative language with lots of neat features, but also suffering from quirks that prevent it from being widely used except by language nerds.
Instead, I'm impressed how much activity there is in the Haskell community, making real libraries like modular database abstraction layers, a distributed source-control system, and apps like an mp3 player, a diagram editor, and even, apparently, a start at a first-person shooter using OpenGL.
I'm leaving out all of its applications in interpreting and compiling languages, since that's its forte. It's quite good at those things, but these wider applications should make it interesting to programmers in general, as opposed to language nerds alone.