The Toronto-based real estate classified site RentCompass has launched a new Facebook app to complement the mobile apps it already has.

The basic concept behind RentCompass is nothing we haven’t seen before – a Google Map with available rentals appearing as house icons. Click any item to go to the property’s details page, which includes the usual goodies – pictures, contact info, floor plans. But in the relatively smaller Canadian market, a small fish can make a bigger splash.

RentCompass has so far been available as a website and as a geo-smart mobile app that shows you apartments in the vicinity of where you are at the moment – i.e., walk down the street and see what’s for rent. It’s available for the iPhone and Android phones.

The Facebook app basically puts the standalone app’s functionality into Facebook. Once inside the the social network’s all-encompassing world, you can like, share and comment on a rental, as well as ask your Facebook friends their opinions too. Given the popularity of Facebook for mobile, it’s a good move by RentCompass.

The company also has a presence on Twitter (with its own app too), but the tweets are just a feed of every new property appearing on the website; it’s not location savvy, making it more of a promotional ploy than a truly functional addition to the RentCompass family.

Listing and searching rentals are free on RentCompass. The company says it’s the first mobile service in Canada for rental apartments and the number one downloaded app in Canada for rental searching.