For anyone that finds the posted site painful on the eyes, here's another introduction to SVD that is all on one page by default and isn't crowded by advertisements.<p><a href="http://www.igvita.com/2007/01/15/svd-recommendation-system-in-ruby/" rel="nofollow">http://www.igvita.com/2007/01/15/svd-recommendation-system-i...</a>