Check out https://flippa.com/ ,and be aware of the following classes of problems:

* It's very easy to artificially elevate visitors as displayed by eg. Google Analytics; same goes for inlinks, site ranks, and any other quantifiable metrics

* Specifically with Flippa, do a historical follow-up on their "just sold" list via eg. archive.org: http://web.archive.org/web/20110611031734/https://flippa.com...

Success/survival rate on the 1-year mark is extremely low; same goes with buying any "sideproject" -be extremely careful what you buy into.