libevent is meant to replace the asynchronous event loop found in event driven network servers. An application just needs to call event_dispatch() and can then add or remove events dynamically without having to change the event loop.
Currently, libevent supports kqueue(2) and select(2). Support for poll(2) and /dev/poll is being planned. The internal event mechanism is completely independent of the exposed event API, and a simple update of libevent can provide this new functionality without having to redesign the server applications.
More information about event notification mechanisms for network servers can be found on Dan Kegel's "The C10K problem" web page.
Manpage: event(3).
Sample Application: event-test.c.
NB: configure magic as always provided by Dug Song, though I am learning.