We probably would have tried that if money was the only objection for event organizers. They had enough other concerns (like giving up access to their attendee list) that made customer adoption of our product tough.

Have you seen what Lanyrd have done in this space ?

Their challenge is w/o the attendee list from the event organizer, it's tough to get a meaningful % to participate.

Lanyrd released in 2 weeks with 1 feature - aggregate the vevents from the people you follow on twitter.