There are already a lot of services that do exactly that. I remember one that was pretty addictive where you'd give feedback on other people's sites in exchange

There are already a lot of services that do exactly that. I remember one that was pretty addictive where you'd give feedback on other people's sites in exchange for points that you could use to get feedback on your own. But some quick googling should turn up a lot of similar sites. And by the way, I don't want to be harsh, but you don't even tell visitors what your service does. How do you expect to convert anyone?