Clickbooth is among the many top leading advertising marketplace where they provide partners with a progressive full-service management platform dedicated to optimizing revenue generation for both its Advertisers and Publishers.

They have tons of Pay Per Lead options which you are paid for simply getting people to fill up some form or doing some action.

What you do as a publisher is to drive traffic to your selected program and you will start making money from generating leads for the advertiser.

However, they have very little International Programs and most of the listed prorams are targeted towards the USA and Canada.

Overall, I think, this program could supplement your income besides Adsense. Give it a try!