aacf4497__Blogger__Tumblr_and_Posterous__0
[Blogger.com] Adsense integration and ability to add any type of advertisement. [Wordpress.com] WordAds - You need a custom domain blog and high traffic before being eligible for it. [Tumblr] You can insert your own ads. [Posterous] You can insert your own ads. [0] 
Your Own Ads
Choosing a Free Blog Host - Comparing WordPress.com, Blogger, Tumblr and Posterous
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