Having 1000 users who have been paid , or otherwise incentivized, to sign up for a service means nothing really as they generally won't be the kinds of early users you need. Plus, this model won't really work if what someone is actually looking for is paying users.
A service to help entrepreneurs to market their web apps effectively so that they reach their target audience/users, so that they sign up organically would have a far better chance of success I think.
This was exactly what I was thinking. I suspect (I don't know of any data on this, but I'd love to see some) that there's a huge gap between users that sign up to a new service because they hear about it somewhere and think, "hey, that sounds neat, I want in first/I'd like to explore" and someone who's simply been paid to setup an account. cf. grassroots (http://en.wikipedia.org/wiki/Grassroots) v. astroturfing (http://en.wikipedia.org/wiki/Astroturfing)
A service to help entrepreneurs to market their web apps effectively so that they reach their target audience/users, so that they sign up organically would have a far better chance of success I think.