flashybrid is a Debian package that automates use of a flash disk as the root filesystem. Useful for semi-embedded Debian-based systems.
I don't use it anymore, having moved on to other tools for similar purposes at work. Diego Iastrubni has taken over maintenance.
It seems to be used a lot still on plug computers: http://forums.plugpbx.org/index.php?PHPSESSID=akj45onst1tkpltrsr6i3abh46&topic=32.0