I've had a similar need in my app, which has been in use since 0.6. I ended up basically abusing child_process.fork() -- every call to a certain rather long-running, possibly exploding async function is made not from the main node.js process, but is actually spawned as a separate process from node. So if it explodes, the core app instance isn't affected. Of course I do some intelligent things such as kill these "worker forks" if they take longer than 30 seconds, and I check for various UNIX signals to watch if they die and react appropriately.

I also tie the worker PID to each user's session, so they can't spawn an infinite number of workers and cause serious strain on the server -- the server just kills the previous worker and spawns a new one if it's asked to run the function again.

I was actually thinking about opensourcing this, but I guess it's pointless now that domains basically do what I hacked together.

Absolutely, although Domains are a new feature in 0.8 and will need some time for maturity.