Not claiming this site is accurate, but I found it useful just now. Allows you to compare new and old model numbers. I'm sure there are sites for other brands. http://www.getsaws.com/S_specs.html
Make sure to get the Earthquakes. I know there's about a bazillion of those shipping in from China everyday.
Posted as a resources. http://firewoodhoardersclub.com/forums/index.php?resources/stihl-and-husqvarna-specs-lists.5/