Iris, concurrency library for C (NSOperation, Twisted deffereds, and CCR in one)
github.com
github.com
http://github.com/chergert/iris/blob/00ba89e06cf457ec5b8f241...
It's primary focus is how to handle work after your event loop. For example, you can saturate your network card on very little use of a single cpu. Iris focuses on how to efficiently use the rest of those cpus for processing.