[andyangelos]

Still in private beta (which does not help) but isocket.com would provide ease in billing, reporting, and adjusting rates. Worth signing up for notifications as a future solution :)

Have never used this http://www.openx.org/ - but removes the rate adjustment problem since you are dealing with a marketplace. Might be worth investigating as well.

[kadavy]

Ahh, you just reminded me to ask about marketplaces. Thanks.