[robflynn]

I implemented a site that had this requirement. Much like the suggestions already here, we found that PayPal was the easiest route.

We used a standard Merchant account (Authorize.Net if I recall) to handle incoming money. For the outgoing money, we had a script that we ran monthly that would calculate the amount due to each member. We then sent that money to each user's paypal account (we required a paypal address upon signup.)

I, too, wish there was a better solution, but I am not immediately aware of one.

I was going to recommend talking to Sahil Lavingia [http://news.ycombinator.com/user?id=sahillavingia] (Gumroad, etc.) as Gumroad does payouts to users based on the items they sale. If I recall correctly, their incoming payment system uses Stripe. It appears that Gumroad also uses Paypal for paying users, though speaking to Sahil may still give you some additional insight.

Best of luck, I hope this info helps.