It turns out that adding adsense made me about $16 in the past half a year. I let it at least get over the $10 mark so that I get paid when I cancel. To make any reasonable money, the pages would have to be much higher traffic than they are. On average (except for really weird days) I would get 200 hits on all the pages with the ad (mostly the diffyqs notes). That translated to at most $2-$3 per month.
Well at least I learned a lot about css when adding the code. Removing the ad might make viewing the pages nicer too. The ad actually adds quite a bit to the page load time (at least it did for my pages).