Ubuntu Linux

Under construction.

Source-O-Matic
Automatically generates a sources.list for you, based on your operating system.
Ubuntu, Ubuntu, Ubuntu
A nice overview created by moma.
Ubuntu Dapper Unofficial Guide
Wiki-style overview.
Ubuntuforums
Official Ubuntu Community Forums.
Ubuntuforums HOWTOs

How to do this or that with Ubuntu. Sorted by rating.
Ubuntu handpicked HOWTOs
Title says it all.