First off, I did do prep work. So it's not like just out of the blue I decided 'today I will make $100 from AdSense with no pre-existing resources'. But basically, this is what I did.
a) (Total) list size of about 7,500
b) Sent them to an offer
c) Had adsense on the offer page
d) Included a few social/share elements on the page, etc.
And it was nice to see that I got about $100+ in adsense revenue.
Point of the post is:
a) I was amazed/pleased to see something that I did with respect to adsense worked nicely. So just sharing that. (I am currently figuring out how to generate $$$ through adsense).
b) Sharing a tip you could try out. Once users have opted into your form, and say are about to leave (haven't purchased, etc) - you could try implementing some adsense code on it. While it might not result in 'tons' of cash, the pennies add up and might be a nice pizza at the end of the month!
[EDIT]: Reading some of the posts, I realize I should be a bit more clear. The $100 was 'after' anyone who had wanted to make a purchase of the main product did, so this was like 'bonus' money... Cheers!