Not only does craigslist.org and backpage.com put eyes on your inventory they also allow you to display your inventory in other locations using RSS.  You can use a variety of other publishing options to present your inventory in other locations on the net.

These other options will further allow us to create additional web assets to drive traffic to your main website and listing in these venues.  Using blogs, squidoo.com and hubpages.com we leverage your listings to provide updated content and search engine domination for your keywords and local competitive markets.