How to build a webmaster payment system?

I'm starting a project that requires me to pay webmasters a variable amount each month, which changes depending on a system similar to referrals/clicks/links/views/etc. I have two concerns;

Tracking - I need reliable tracking for this stuff, so I pay correct amounts and have full information in case of disputes. And I also need to detect fraud. Unlike Google. Mahah.

Payment - I need to somehow print and mail cheques, or find a method of easily paying people without too much hassle.

Do you know of any software packages that can help me with these? Free or paid. Obviously I can write the system itself, but I'd like some rock-solid off-the-shelf solutions to the administration/payment side of things.

Or have you set up a similar venture, and have some wise words to share?

I look forward to everyone's comments

 

Couldn't you use some type of banner ad system?

And chances are that your market will have Paypal so you could potentially sign up with them. And then transfer money that way. (I would make it that they have to have at least XX amount in their account before payment.) And then if they do not have Paypal but want a check, maybe double that amount or 150% of that amount.