Smowtion is a good alternative to adsense. Actually you can work with both ( see the web page ) To create your account and start monetizing with Smowtion was really easy and if you have any problem you have an account support for you what is cool. They have really good quality ads I would recommend to give it a try!
There is no Alternative of adSence but if you would like to join other ad-network with Google then you can choose infolinks or AdBright.
stay away from them. If not too many people have heard of it, avoid it. Other options out there....more popular ones like Chikita, konrea, etc....
Yeah all are right here. smowtion is the new thing I have never heard before. And no one is the competitor for Adsense.