Just as marketers are getting a handle on Facebook, Twitter, and YouTube, a fresh group of social media networks are poised to make a splash in 2010.

These networks have not reached mass adoption yet, so it’s not necessary to get active on all of them immediately.  But remember, Facebook only took 6 years to reach 400 million registered users.  You should keep an eye on these five upstarts to see if their innovative services attract large audiences in the near future.

Why You Should Pay Attention

Learning the ropes on new services before they gain mass traction can help you get value from them faster once they catch on.  Monitoring the innovations in the social media space also gives you an indication of how the market is changing and will evolve over the next few years. Marketers should stay abreast of broader market trends to assure their messages stay relevant.

The 5 Social Media Sites You Should Explore

#1: Foursquare – This location-based social network/gaming application is rapidly gaining users and mindshare.  Users “check in” at local businesses and earn rewards for frequently visiting participating establishments.

The site receives more than 1 million check-ins per week.  Business owners can get value out of Foursquare by offering incentives for users to check in, such as special offers for repeat visitors.

The site lists more than 800 establishments currently offering deals.  Those deals could include a free drink or appetizer for the Foursquare user who checks in the most (called the Mayor).

Currently available in 45 US cities and many major international cities, Foursquare has plans to expand further and grow its user base over the next year.  It has also signed major partnerships with TV network Bravo and restaurant guide Zagat that will expand its functionality and usage.

#2: Google Buzz – Google’s latest entry into social networking has the potential to attract rapid adoption, due to its connection with the widely used Gmail and Google Maps applications.

Buzz allows users to post status updates and upload pictures and videos to a Google profile, not unlike Facebook and Twitter.  A user’s network is formed by contacts they interact with frequently on Gmail.

If a user makes an update public, the information also gets added to the “Buzz” layer now available on Google mobile maps.  Now, Google Maps users on iPhones and Android devices can view the things other Buzz users have said about businesses in the area.

#3: Loopt – Another location-based social service, Loopt aims to connect its users with their friends by visually displaying their location and availability on a localized map.

Users can connect with friends in the area, see reviews and recommendations of restaurants, and find events in the area that might be of interest.  Businesses have tapped into Loopt’s location data to offer targeted promotions.  The B.R. Guest restaurant chain in New York sent messages containing special discounts to Loopt users near their restaurants.

Loopt is accessible on more than 100 mobile phones, giving it the widest distribution of any of the location-based services.  It is currently used by about 3 million people, which should increase as Loopt expands to more cities.  Marketers should explore the possibilities of interacting and promoting their businesses through Loopt, as well as monitoring posts to judge the sentiment of user reviews.

#4: Blippy – Blippy aims to connect people around the purchases they make.  Easily the most controversial of the applications profiled here, Blippy publishes the amount and location of customer purchases (with user permission, of course), which the rest of the community can then react to.

While the concept may not seem attractive on its face, the site has already signed partnerships with a dozen major vendors and is funded by many marquee investors.   If the service begins to attract a large user base, this community could be very valuable to retailers looking at general purchasing trends.

#5: Groupon – This site offers “collective buying power” by providing deals to groups of people who buy products and services in bulk from participating retailers.  The site uses social networking to get users to share offers with their communities, in order to reach the target number of customers the “Groupon” requires to activate.

Businesses could gain exposure and new customers by making offers on the site—if Groupon develops a large following. For instance, a colleague recently bought a golf lesson package from a local pro shop for 60% off, because he joined a group of 29 others in the “groupon.”  While the revenue from the purchase is helpful, exposing a large group of customers to your product is even more valuable.

This is by no means an inclusive list, only 5 exceptional companies striving to change the social media landscape with fresh ideas.

Which up-and-coming social application are you most excited about? Who did we leave off the list that should have been included? Please leave a comment below…