Suggestion: Facebook comment plugin with many sites ..
Alonge with wordpress comment platform , jcomment and many others we can do something with facebook also .
Yep you can't create dofollow links and many of them are not seen by search engines as nofollow either , but all search engines can undestand them as facebook share .. So as social signals , and we can't turn our back on this . We need social signals for seo. and its simmiliar to promotion too.
I can't code the engine i am sure it will be very tricky and diffcult to accomplish, and i am very new to code this one , but i can share the footprints to find those sites that have facebook comment platform "yeah this is the easy one" but mine footprints is in any language. and this one its not so easy 
Also i know already the frequency you can post to don't get banned and everything we need to know so we don't get banned. we need to create this engine ..