I noticed that a lot of websites are offering to share their adsense revenue. Is this against Google Adsense's TOS?
Not technically, but you need to be careful about newbie or dishonest users who click their own ads. If you're sharing revenue by showing your ads AND their ads, alternating, they may click your ads as well. It's highly doubtful anyone who wants to cheat the system would take the time to check the source code each time before clicking only theirs. Adsense API is a better way to go, because Adsense just shows their ads and then Google pays you part of the take of users on their site. Therefore, if you've got someone who has the bright idea to click their own ads they're likely only going to hit their own and it's presumably easier to identify the problem user. Unfortunately, Adsense API has a 100K pv/day requirement to get in at the moment, which is way beyond most sites. You might watch and see if they lower it. It's a technical bear to implement, but seems to be a nice solution to the click fraud issue. (I got in early, before they instituted that limit.) -- Leva
I was going to say basically what Leva said - it's OK, but the more safe and secure way is through the API. Google has to review and approve every implementation, technically and administratively. It does take a bit of effort to get going, but there are a lot of advantages... it was well worth it.
Take a gander at this list of adsense revenue sharing sites and info. You may like to check out who's doing it.
Take a look at the link in my sig (on right). Toward the bottom of the page, I list various platforms that have mods for revenue sharing.
no... it's not, even the program like flixiye.com , is adssnese revenue sharing , i think this site is the own of google.com