Well, this is very interesting question, which bugging me for months, how not very big sites with indexed 10K sites, and backlinks index by google just 2, being rank 45k on Alexa, my site much bigger and google indexed 77k, with 78 backlinks indexed by google, has much worst alexa rank 130-150k range. any tools out there to see where traffic comes from for my competition or any other site? i still did not find any good once. thanks
Try using SEOMoz OpenSiteexplorer, that should help you analyze your competitors sites and webpages almost thoroughly.