$2-$5 for 100 US visitors a day? I'd call that pretty nice if you ask me. I'm only getting $0.04 a click from my US visitors on Adtoll.
Better than a kick in the head no? At least you are making money, look at it that way. Might wanna try and see if you have other ways to generate income from the site.
it's also nice for me, just continue to promote your site for more chances to gain traffic and also with fresh content.