ExoClick is nowhere near AdSense, but they're still only a small fish in a big pond. If you sign up they've got a tool which tells you what different keywords typically pay. In my experience they pay pretty poorly. On my webmaster related site I only get maybe 1 or 2 cents per click so I dread to think how low they could pay for an even more popular niche. Having said all that, don't dismiss them out of hand - if you've got some space to fill you'll make more from ExoClick than leaving a gap in your page.
No one pays close to Adsense... because in my opinion Adwords customers are getting ripped off but they are still willing to pay..... yes some get great ROI but I bet half don't even know what ROI they are getting and are just concerned with "being at the top" and getting ripped off and driving up bids in the process.
Lol! That really sucks, only 3 cents. I tried Exoclick, not only once but twice :| And they were nothing by "AWFUL" I am sorry but thats the truth.