No idea is a bad idea !! And what works only they (world) can tell. Who knew the 140 characters could have revolutionized the world creating a parallel universe... So.. try it.. you never loose..

My personal opinion - I like it. There are some startups I have heard of who are doing the same thing for Social causes.

E.g, I can give away my time, or service (book keeping if I am an accountant). Money etc.

In nutshell, unlike Fiverr, freelancer or Guru, you currency is not money but "sweat currency". I am sure there would be marketers who can ask a programmer to create a website and in return help them with building there social media profile. I would do it .. so you already have 1 customer. I am willing to pay $9/Mo just to be on a platform, if there are more people.

Revenue Models -
1) Advertizing - this is for the dumbest of all.. Spoils the user experience. Had it been year 2000-2005 , i would have said ..go for it !!
2) Feature lock Freemium model - Like linkedin
3) Mail chimp model - where you limit the numbers for free customers

I see a potential.

You main concern here is not the revenue. I guess , it is the growth ! 2 sided market places are the toughest ones .

If we want to talk to me .. feel free..
I am willing to spare 30 mins (free) if you are not in a position to pay..
I love idea brainstorming :-) get a high from it !!!