I have been looking at Digivate’s Wordpress Plugin as an alternative to Google Adsense.
Quote from Digivates site
‘It’s a wordpress plug-in that adds a randomly generated text link sentence to the bottom of each blog. The set of sentences you get will be relevant to your blog and looks more natural and less intrusive than other ways to monetize your blog. ‘
It seems to be quite a good idea might give it a shot and see if this sites up to scratch for their terms.