http://botdomains.com/ - specializes in robot, robotics and bot domain names.

http://www.domainhack.com/

http://geographicaldomains.net/

eBay http://business.shop.ebay.com/

Flippa (was Sitepoint Marketplace) http://flippa.com/

Sedo http://www.sedo.com/services/s_buyproject.php3

Website Broker http://www.websitebroker.com/

BuyMePrivate http://www.buymeprivate.com/

Dealasite http://www.dealasite.com/

Tidget http://www.tidget.com/Websites

WebsiteSlate http://www.websiteslate.com/

Webmasters Marketplace http://www.webmastersmarketplace.com/

BusinessBroker

BizBuySell

BusinessesForSale

Business-Sale

BizSale http://www.bizsale.co.uk/websitesforsale.html

BizQuest http://www.bizquest.com/buy-a-business-for-sale/results.asp?i=16&l=

DaltonsBusiness http://www.daltonsbusiness.com/buy/online-businesses-for-sale

Dealabiz http://www.dealabiz.com/

InternetBusinessesForSale http://www.internetbusinessesforsale.co.uk/

WebsiteProperties http://www.websiteproperties.com/websites-for-sale.asp

DigitalPoint http://forums.digitalpoint.com/forumdisplay.php?f=52

DnForum http://www.dnforum.com/f48/

NamePros http://www.namepros.com/domain-names-with-traffic-stats/

GeekTalk http://www.geekvillage.com/forums/forumdisplay.php?s=&forumid=61

SearchEngineForums http://www.searchengineforums.com/buy-my-website/i/

V7N http://www.v7n.com/forums/websites/

WebhostingTalk http://www.webhostingtalk.com/forumdisplay.php?f=134

Webmaster-Talk http://www.webmaster-talk.com/websites-for-sale/

DaniWeb http://www.daniweb.com/forums/forum164.html