I can't believe that there isn't a "google" topic...
Anyway. I've added google adsense ads to my book review site. The basic idea is that google already know what my page is all about, so it will be able to intelligently target ads at my site.
I seems to work - to some degree. My front page has some okay links at the moment:
* Free Sci-Fi News
* SF&F First Editions
* Free Reading Group Guides
* Robert Sheckley's Books
If I browse through my author pages, the Sheckley ad may or may not be there, but most importantly it in my robert sheckley page.
The not that great thing is that it isn't on my Dimension of Miracles page (it's a novel by Sheckley). Infact this page has nothing but charity ads, which I do not make any money of. I'll hold off my final judgement on this for a couple of weeks, and see if it changes as google (hopefully) gets to know my pages better.
Oh, boy am I going to make a killing on this? I think so! The last three days has given about 500 ad views, three clickthrougs and 18 cents(*) for me!
(*) no it isn't even euro's, but us$, so it's even more worthless...