I know this thread is a bit dated, but I came across it through Google so I thought I'd add my two cents:
I agree with the posters above who mentioned affiliate retail. I've developed a few sites that rely entirely on affiliate revenue, and I much prefer it to selling ad space. The revenue per click is usually much higher, and I have additional control over which retailers I work with.
I've worked with Pepperjam Network, Google Affiliate Publishing, Commission Junction, and Avantlink, and can recommend all of them. In particular, Avantlink is great if you would like to sell specific products for certain retailers rather than just banner ads.
For an example of how affiliate sales have worked with our company, feel free to check out one of our projects, a hub for discounts on outdoor equipment: TrailLove
Founder - Nineteen Ventures, LLC