It is unclear if Google allows people to do revenue sharing with Google AdSense. For example, back in May of 2004 DigitalPoint Forums began a revenues share AdSense program. Basically, you can plug in your AdSense Publisher ID into your profile at DigitalPoint Forums and for every thread you create, you can share the revenue with the forums.
If you have an AdSense account, you can enter your client ID here. You then have a 50% chance that the AdSense ads displayed are credited to your account on threads you participate in.
But is this allowed? There is no direct answer in Google's Terms of Service but one member has a long Q&A thread with Google at DigitalPoint Forums. One question and answer reads as follows:
Q : Is it allowed for displaying the google ads code at any sharing revenue forum?
A : Please note that Google does not endorse or encourage the use of ad code rotation. We recommend that you review the AdSense Terms and Conditions found on https://www.google.com/adsense/localized-terms, and exercise caution if you choose to rotate the ad code on your forum. All AdSense participants are responsible for ensuring that pages showing their ad code comply with AdSense policies and that invalid clicks are not generated on sites showing their ads.
It does not discuss revenue sharing but it does say that they do "not endorse or encourage the use of ad code rotation." Heck, I use ad rotation here.
The second part seems like if your publisher ID is on a site that generates invalid clicks, you have to be worried. So if for example, DigitalPoint forums generated invalid clicks (not saying it does), and you plug in your AdSense ID and someone clicks on the ad, when your AdSense ID is present, then you are held accountable. At least that is how I understand it.
Forum discussion at DigitalPoint Forums.