Monetize multiple domain names?

My client has over 100 domain names registered and wants to know how to monetize them so he can earn at least $50/month from each domain.

I thought of building him niche websites using Adsense and Affiliate programs but it would take a long time to create enough content before generating a profit. Even if he spent $1000 to develop each site he would only make $600/year at $50/month. Perhaps the site would be profitable after 2 years.

Any suggestions?

You might consider possibly flipping some of the domain names. Take the better names and make a few sites. And also check into domain parking at Sedo.com.

Thanks for the tips.