Question about listing your rental online without an agent

I have a rental that will be vacated in the next couple of weeks.  In the past, I just put a sign in the front yard and had no issues leasing out the house.  I honestly think I was lucky.  Previously, I believe I read somewhere in a forum that you can draft a single listing in a template and it is posted online at multiple sites for free, including pictures.

What was the service? 

Also, any advice for how to best use the template/service would be greatly appreciated.

Thank you.

Steven