Using Moonscript (Lua's CoffeeScript) the performance benefit of LuaJIT when compared to all JavaScript implementations makes it a really interesting.
Well, actually Lua doesn't look bad, even though it really needs syntactic sugar for OO, but there is enough of it. Not just Moonscript, but also Loose (Perl's Moose ported to Lua).
1. Mozilla's Rust http://www.rust-lang.org/
2. Tim Caswell's LuaNode https://github.com/ignacio/LuaNode
3. Ben Noordhuis and Bert Belder’s Phode async PHP project https://github.com/bnoordhuis/phode
4. Kerry Snyder’s libuv-csharp https://github.com/kersny/libuv-csharp
5. Andrea Lattuada's web server https://gist.github.com/1195428
6. Steve Yen's Lua wrapper https://github.com/steveyen/uv
Source http://blog.nodejs.org/2011/09/23/libuv-status-report/