First off, have you taken a look at node.js? JavaScript is one of the languages that, over the last few years, has seen leaps and bounds of development, and its likely to keep growing.
In terms of functionality, it is less mature when compared to other server-side technology, but the active community is making it not far behind.
Finally, since its a language that runs on both the front and back-end, its implications for code-reuse and data-exchange formats make application development a whole lot faster.
I'm not sure its quite ready for production yet (unless you yourself are willing to contribute to the code-base) but server-side JavaScript is a good option to experiment with.
