That idea is so good you should have kept it to yourself and came out with your own offer.
But now that it's out in the open, let's get the ball rolling on this.
I'm actually planning on that, I've got 3 other good offers in mind, one of which is already running on facebook (just an e-book) and it's doing really well. If I set it up as a $3 trial and did rebills I know it would do way better but the biggest issue so far is finding a reliable merchant account provider that can do rebills. I had a good one back in 2004 but his emails are bouncing and the phone number is no longer in service

