Art Whitton's web site has been around for about 7 years, offering the best in free online training for AutoCAD. The lessons are adapted from a 4 level course he developed for new AutoCAD users. Originally, the tutorials were deigned for Release 14 and have now been updated and adapted for AutoCAD 2010. His approach has always been to teach the commands in their context and in a natural progression. Each tutorial also has a quiz to help students review. The older lessons for R14, 2001, 2005, 2007, 2008, and (as well as the current 2010) are available on CD.
The CD also has tutorials in Spanish for 2005 and 2007.