Rumors are swirling that Google is set to buy Groupon for around $5 billion. Although Groupon is the first and biggest player in the group discount game, there is an ever-growing number of alternatives that are expanding to new cities.

These group-buying sites are able to provide deep discounts on items and services when a large volume of consumers sign up for the particular deal. Often it's a slashed price on a meal, spa service, and a limited amount of time is allotted to purchase a limited number of coupons, organized by location.

According to an August Business Insider report, LivingSocial.com is the biggest competitor on Groupon's heels. In fact, according to July statistics from comScore, LivingSocial gets just slightly less traffic than Groupon.

LivingSocial is also one of the more widely available discount sites, doling out deals in more than 100 locales in five different countries including the U.S., Canada, Australia, Ireland, and the U.K. Groupon, on the other hand is offered in more than 40 states in the U.S. as well as 28 countries around the world.

HomeRun.com is a similar system that works in 33 cities. Collective buying site Tippr.com currently serves 12 cities. It sends out three location-based deals via e-mail each day featuring 50 to 90 percent discounts. DealOn.com, meanwhile, encourages shoppers to share the coupon with their friends by dropping the price when more users sign on for a particular offer.

With an iPhone app, ScoutMob taps into the phone's GPS system to give coupons based on a users' current location. It's only available in Atlanta, New York City, and San Francisco for now, but the company has plans to expand to 10 more cities.

The social-buying site consumers use depends on their location. While these services are a dime a dozen in cities like New York, Chicago, and San Francisco, residents of smaller cities have fewer options.

But with a wealth of coupon sites to choose from, it can be dizzying to try and find a deal. Aggregation sites make it easier. Yipit.com combs through about 130 group coupon sites like LivingSocial and Groupon to give the best deal recommendations based on a user's location. It's currently available in nine cities.

8coupons.com is another coupon aggregation site. It provides a list of all of the available deals in a certain area when a user provides his or her zip code.

According to a New York Times blog post, the proliferation of group deal sites has spurred the creation of a secondary market. Lifesta.com and Couprecoup.com are two sites where people sell their unused deals purchased through companies such as Groupon.

But it's not just niche sites that peddle discounts; social-networking sites have created special offers for consumers as well. Recently Facebook launched Facebook Deals, a feature that offers discounts when a user checks in at different locations. Location-based service Foursquare offers similar options, and search service Yelp now lets businesses offer incentives for check-ins.