You know what? I'm impressed by the way Google is exploiting Blogger. The ads at the top of my blogs are becoming far more relevant. Today I noticed BeatBlog is accompanied by adverts for sample CDs and samplers. How did they work that out? From the contents of the page?
To a human it's obvious, but most of the words are rather colourful descriptions of my beats, not actually much talking about "samples" and the like. And there's now a big chunk of stuff about pornography, which clearly hasn't triggered XXX site ads.

I wonder if Google do some kind of second order relevance analysis. Just as PageRank works on pages linked to and from, does their ad-relevance analysis use the subject of pages linked from and to my blog?