Linux is a freely available (Think Free Speach, not Free Beer) operating system. Similar to the various UNIX operating systems, Linux provides a multiuser enviroment with strong networking support. For more information, please refer to a Linux distributor such as Red Hat Software, Caldera, Inc., or SuSE.
LUAU is Linux Users AnonymoUs, a Hawaii based user group dedicated to offering support for people interested in using Linux. Unfortunately, Linux is currently not an operating system that is easy to work with. While this issue is being addressed, it will likely be some time until it matures as an end user operating system. For more information about LUAU, check out the LUAU homepage.
Currently, I am working on a few projects for LUAU. If your intested, here is a list of projects that I have worked on.