Tim is correct in that you can list as many properties as you desire for free on the Trulia site. Your local MLS may feed the listings into this site as well as other real estate related web sites.
You still have the ability to edit copy, add photos and a virtual tour, and post Open House Times when you click on your listings tab (under your name in the upper right hand corner of the screen) to make the changes.
And...landlords who are not RE agents or Brokers can also list their rental properties on this site too.
Good luck to you!
Prudential Connecticut Realty