If you have a thriving list, you may have already considered expanding to include a newsletter or ezine offering. Maybe you've abandoned the idea because you just don't have the time to manage another online activity. Partnerships come in many shapes and sizes.
Owners maintain their own properties and revenues but work towards mutual benefit.
The partnership is flexible but provides limited branding opportunities and there is no revenue sharing. Owners work toward common goals for the single entity while revenues remain separate or partially-shared. The partnership is still flexible and branding is stronger, but individual branding is lost. A shared revenue partnership offers the least flexibility but the greatest opportunity in terms of profit because there are effectively two people working to promote and sell the combined site. However, you will probably have to work out a percentage split beforehand because one person will most likely be bringing more resources to the partnership than the other.