While rentals do exist, it is fairly uncommon. Developers generally don't want to put time and effort into building a site and traffic only to have the rental expire and the domain owner reaping the benefits of their work.

My recommendation would be to either sell the domains that you are not interested in developing or enter a joint venture with an experienced web developer/promoter. I have entered into several agreements of this nature which has allowed me to have access to some premium domains. A portion of the revenue the site generates goes back to the domain owner.

Cheers!
Chris