Once I saw a thread in Old BHF:How Do I? I advised to use Google groups. Now extending this idea, The forum can be embedded inside your blog pages/posts/widgets etc., All you need to do is Create a Google Forum. After creating, copy the below code,
Although already posted "How to add social bookmarking buttons on blogger?" lets see a bit altered form of social bookmarking buttons. First download the code from here.Go to Dashboard => Design => Add Gadget => HTML/Java script gadget[Old UI].Dashboard => Layout => Add Gadget => HTML/Java script gadget[New UI].