Generally, its not something I go in for on blogs. Hypocritically, I tend to use adblock software on the vast majority browsers I use. However, not too long ago, I set up Google Adsense for this blog. I've got them set to be an unobtrusive as possible, and not to advertise using your browsing history.
I'd rather the advertising sell you things germane to my blog rather than something to looked up on Amazon on a lark. I just like a certain cohesion.
I signed up for almost a month ago, and I never received word from Google that it went live. Alas, help toss me some spare change for coffee and click on an ad from time to time!
I will also continue to unblock more and more pages I like.
I just really hate ads based on my browsing history, or you know... porn being advertised at inappropriate times.