Ultimate Blog Marketing

Google is the best contextual advertising program around because it has the most number of advertisers, which means more competition and bidding for keywords resulting in higher earnings for publishers
But you can try
Yahoo! Publishing Network (currently in beta and available to US publishers only) http://publisher.yahoo.com/
Intellixt http://vibrantmedia.com/site/web_01a5.ht…
Quigo Adsonar http://www.quigo.com/adsonarexchange.htm
IndustryBrains http://www.industrybrains.com
Commission Junction Evolution http://www.cj.com
Kanoodle Brightads http://www.kanoodle.com/about/brightads.…
Clicksor http://www.clicksor.com/affiliate_progra…
Contextweb http://www.contextweb.com/
Bidclix http://www.bidclix.com/
Bidvertiser http://www.bidvertiser.com/
Also consider banner ad networks
Burst Media http://www.burstmedia.com
Fastclick (ValueClick). http://www.fastclick.com
Advertising.com. http://www.advertising.com
Tribal Fusion http://www.tribalfusion.com

If you are earning money with ad-sense, then take a look at CPA (cost per action). or affiliate link as they are better known. Ad sense is OK, and I earn a fair amount from it (I am a full time SEO internet marketer) , but affiliate systems will give you a far better return Thai]n ad sense if you are getting targeted traffic.
Try azzogleads, commission junction, or click bank for this information.
A word of warning however, NEVER click on ads on your site, and NEVER ask others to osuggest they can. Because google WILL close your acount before they are due to pay you. Google has excellent click fraud automated software, and any behaviour that falls outside of normal, raises a flag.
You have been warned