Daemons provides an easy way to wrap existing ruby scripts (for example
a self-written server) to be run as a daemon and to be controlled by
simple start/stop/restart commands.

If you want, you can also use daemons to run blocks of ruby code in a
daemon process and to control these processes from the main application.

Besides this basic functionality, daemons offers many advanced features
like exception backtracing and logging (in case your ruby script
crashes) and monitoring and automatic restarting of your processes if
they crash.

WWW: http://daemons.rubyforge.org