AutoCAD 2005 and earlier doesn't have a way to dimension arc length, but Leonid Nemirovsky has come up with an AutoLISP routine that dimensions arc lengths very nicely. You can download it here.
This is the 9th edition of this book! Completely updated to conform to the new interface and, of course, it covers all the new features, such as the ribbon, Quick View, ShowMotion, the View Cube, the SteeringWheel, and more.
AutoCAD 2008 and AutoCAD LT 2008 Bible Learn the great new features with wide application to all disciplines. Get the most comprehensive book on AutoCAD! DVD contains a 30-day trial of AutoCAD and AutoCAD LT. Thorough exercises guide you through each feature.
AutoCAD 2007 and AutoCAD LT 2007 Bible Discover the 2007 features, especially the radically improved 3D tools. CD has AutoCAD 30-day trial, 3rd-party software, and drawings for exercises.