It's hard to make a website that pays itself, and if you force people to pay to see some content, you're gonna loose some audience, even if it's really cheap. You could just put a paypal link or something for people who like what you're doing, like a donation system. People always pay more if they're not forced to do so ;)

Now to make the website "social", it will have to be dynamic (comments, votes, likes, etc..), so you'll probably need some "heavier" blog engines like wordpress and the like (heavier than jekyll and such, that is).

After that, I love the idea of a community driven blog ! It let people not having a blog express themselve, and you'll obviously get some golden content from it ! I really want to see this happen, but be careful not to let everyone post. there are spammers everywhere, and your site could turn into a big trash blog after that. You'll need a subscription system, or even better, a white list.

Finally, if you want more ideas, here are some:

• Host your own image gallery, so that you could show pictures to your family and friends from everywhere. the "Cloud" OMG
  
• Create package repositories for your distribution, so that you could contribute to the community
  
• Provide mirrors for downloadable content, like software (this one need a bit of work to get up to date)
  
• imagination...