I've had best responses with Amazon's affiliate program. Made about $130 bucks from something like 5 or 6 blog posts. Hourly rate worth it? Nope. Was it fun? Yep. Basically what I've learned is that Google's dynamic ad placement is the last thing you should try. Putting in an ad (or affiliate link, there are even services that will auto do this with Javascript, so you're users wont see and you don't have to be part of a billion referral programs. Gray hat? Maybe.) that actually targets what you are talking about is so much more effective.

On that site I make $100-$180 month from affiliate sales, $5-$10 from AdSense.

If you are dealing with physical products then affiliate programs can work quite well.

Edit: On my friend's site is is all AdSense. His is non-physical product related.