I put google ads in the top corner of my blog for a few weeks to see what happened.
When i've visited it, the ads seem kinda non-specific. I guess my content isn't good enough to get good ads?
In the 5 weeks I've had googles showing, I've had 796 page views (as far as adwords is concerned) and a single click worth 28p (= USD 0.45).
So pretty much not worth polluting my pages for and I'll take them off again, I think.