A while back I started to mess around with lua + libuv, and found it pretty easy to write "blocking" functions that would yield to its caller a function responsible for setting up the requisite events to wake itself back up.

If you want to see what this would look like, it's extremely ugly since I didn't work on it much (as it was easier to just use luvit and node-fibers), but I did put it up on github at http://github.com/dyselon/loquat, and you can see examples of it in the timer example of the readme, and the uncommented parts of examples/test.lua. Maybe it'll be of some use or inspiration to someone.

There a lot of cruft in those examples, but in practical usage, everything but your blocking calls would be hidden behind libraries. It's pretty easy to set up similar fiber-friendly wrappers for your favorite node.js libraries, too, if you're fond of the node-fibers add-on.