It was reasonably popular, but difficult to predict usage. You can still see it there - it's not labeled as such, but it's the "Starter" plan -- this will bill you per hour, with a minimum of one per week.

I'd be interested in hiring for hourly work, but I'm not sure how much work I need to send out per week. I suspect others are like me. It would be nice if we could pay a monthly maintenance fee and then just pay $10/hr, or whatever. It would be even better if we could just pay $15/hr during spike times.