"HowtoForge.com. This assortment of contributed content now
includes around 2,000 tutorials. Nearly half of these deal with
various Linux distros, including more than 200 Ubuntu-related
howtos; the remainder cover all sorts of open-source applications
and sub-topics. Everything is available for free, although paid
subscribers get access to some often-useful premium services.
"The Linux Tutorial. Author and IT expert James Mohr has
assembled an impressive set of resources for Linux users. This
includes over 300 articles on Linux-related topics, a glossary, a
huge collection of links to other useful Web sites and a
rapidly-growing forum. Everything is available for free, and
donations are accepted."