RentSocial.com is a new website using social networking to search for an apartment. Similar to the consumer-reviewed site Yelp, users can leave remarks of buildings they currently or used to live in. You can also create your own RentSocial profile using your info from Facebook. The site gives an “activity feed,” where building owners, friends and neighbors can post messages. It’s all free of charge to users (the site makes money by charging building owners a monthly fee to be listed).