We ran a very successful After-School club program this year, netting the PTO $4600!
We had the following clubs running: Zumbatomic, Tae Kwon Do, Drama, Mad Science, and Lego. They all ran for 4 weeks, although we had to reschedule a few dates due to snow days here in PA. We kept the cost relatively low, and had each club fill within a few days. We did not do any club as a "grade-level specific"...that has been done in the past, and seemed to confuse both parents and our front office staff.
We used outside vendors for all but the Lego club....and due to the cost of the Legos, we got a sponsor for that club. Our biggest hurdle this year with clubs was getting volunteers to help staff the clubs....they seem to be low cost babysitting.