Crowd "booter"

I signed up for Crowdbooster on a lark a while back – someone probably linked to them on Twitter. I think I get a weekly digest email from them telling me how many followers I’ve gained/lost. This is a great example of a service that probably should have been “freemium” from the start (assuming they had compelling “upgrade” features) instead of offering free accounts and now having to try to get people to pay.