You may post your free ads on the following sites. For example, you can post free classified ads on http://fuelspace.com and http://yourads.costfreehost.com AND share the Google Adsense revenue.

http://fuelspace.com
http://yourads.costfreehost.com
http://clickdollars.site88.net
http://articles.costfreehost.com
http://ledbetter.freepgs.com/classpro/viewads.html
http://costfree-ad.co.cc
http://medicine.armed.us
http://fuelspace.com/more-free-advertising/
http://yourads.costfreehost.com/free-advertising-forum/