Check-in apps are all the rage in the mobile space, but these days users aren't just checking into business and landmarks. Apps like Miso and Facebook's recent acquisition Hot Potato, which allow users to check-in to movies, TV shows, books and other activities, have been part of the fuel behind the recent check-in craze. Another player in the "check-in to anything" game is GetGlue, whose popularity ballooned after the launch of its iPhone app earlier this summer. Today, the startup hopes to build on its success with the release of an Android app, a mobile website and new brand partnerships.

GetGlue allows users to check-in to any of a number of activities (like watching a show, listening to music or reading a book), as well as rate and receive recommendations based on their tastes. The service launched as a browser plugin and Web app in November of 2009 but saw a large bump in usage this summer with the release of its iPhone app. Today, GetGlue reports seeing over 5 million average monthly check-ins across its system, the lion's share coming from its mobile app.

"When we launched on the iPhone, we were genuinely shocked at the amount of requests for the Android version." GetGlue VP of Business Development Fraser Kelton told ReadWriteWeb. "The Android app is meant to be as close to the iPhone app's look and feel as possible, and we're happy to achieve that."

The startup hopes to eventually build apps for its users on other mobile platforms, like BlackBerry, webOS and Windows Phone 7. In the meantime, GetGlue is launching a mobile website optimized to provide much of the same experience of the apps to these users. From the mobile site, users can check-in, view a stream of their friends' activity and earn points and stickers regardless of which mobile OS they run.

GetGlue's point and sticker system, which closely mimics that of Foursquare's points and badges, is also receiving an update today with new partners and exclusive stickers. Among these are Barnes and Noble, HBO, Showtime and Internet TV network Revision3. Users can now earn stickers for popular shows like Weeds, new movies like Scott Pilgrim Vs. The World and Revision3 shows and personalities like Veronica Belmont and Kevin Rose.

While the service has seen substantial growth since going mobile, it could face stiff competition in the near future. Hot Potato, a service with much of the same "check-in to anything" functionality, was recently acquired by Facebook. Now the social network giant is expected to make an announcement surrounding location as early as Wednesday. It wouldn't be surprising for Facebook to relaunch Hot Potato as a global check-in service working in conjunction with the site's new focus on "Likes."

Facebook's sheer size could spell trouble for GetGlue, but the startup's ace-in-the-hole could be its powerful recommendation engine, which Hot Potato lacks. As users check-in and like things on GetGlue, they are fed increasingly better recommendations based on their interests and those of their friends. This leads to more check-ins, creating a powerful feedback-loop for the service.

Exclusive deals and expansion to Android and other platforms via the mobile Web are smart steps for the startup as it attempts to position itself in front of the competition. However, only time will tell for services like GetGlue as the location and check-in landscape could dramatically change when Facebook undoubtedly enters it in the near future.