aacf4497__Blogger__Tumblr_and_Posterous__0
[Blogger.com] Bunch of Free Themes from them or you can create your own theme. [Wordpress.com] Free/Premium Themes available but no custom themes allowed. [Tumblr] Hundreds of Free/Premium Themes or you can create your own. [Posterous] Few Free Themes available and ability to create your own house. [0] 
Themes
Choosing a Free Blog Host - Comparing WordPress.com, Blogger, Tumblr and Posterous
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