This website allows you to create an account and prepare VERY EASILY a cool online virtual flyer for rental properties or properties that are for sale and is available to real estate agents and your everyday user. Once created it will automatically syndicate to all appropriate online services opening the door to literally thousands of potential renters or buyers. You may also follow the easy instructions to copy and paste the HTML code to post an ad on Craigslist.
I utilize this not only for my personal properties, but as an additional service to my clients. Creating extra exposure. Here is an example of a virtual flyer that I have posted on Craigslist:
Best of luck to you!
The pennysaver also lets you advertise on-line for free, but I've never recieved a response from them. I also got a lead off of WestSideRentals.com (another free advertising site).
Good luck. I hope you get it rented soon.