I too signed up for Nuffnang in the past, tried inserting their code for like 1 week and I didn’t get a single cent so I removed them.
Then I learnt from Agagooga that you will only get paid when advertisers choose to place their ads on your blog and purely displaying the Nuffnang default ad will never yield you anything. So ya, much wiser to stick to Adsense. 😀
Anyway, not my blog, just thought that it raises some interesting points.