We take flat 5% service fee.
bitcoinadvertisers.com has a 1% fee.
thebtcnetwork supports image ads.
and tons more features, we already have flash/video ad usage in the system, but we are not going to run with this until other areas are perfect.
Please be advised we are literally just launching, and there may be a few issues to iron out so please contact us of anything you come across that may need looking into.