Pokerstars does not and will not ever offer a % deal. If your into promoting CPA it is not a terrible site to promote as there is alot of brand recognition there, especially around WSOP time.
I don’t heavily promote them but I do have a few banners and reviews on 3 or 4 medium traffic sites. You will definately get conversions, it’s just too bad that they don’t offer mgr%, because their software is easily one of the best out there.