Top group-buying sites
Where deals are available: More than 150 cities in the U.S. and Canada and 23 other countries.
What makes it unique: Being the largest social buying site, Groupon has applications available for both the iPhone and Android devices, unlike many other sites of its kind.
Just how valuable is it? In 2010, Groupon was said to be considering selling itself to Google for billions.
Where deals are available: Features deals in dozens of U.S. cities, Canada and four locations in the United Kingdom.
What makes it unique: In addition to its iPhone app, LivingSocial has two popular Facebook applications, Pick5 and Visual Bookshelf, which allow members to share their favorite things with friends.
It has deep pockets: In order to keep up with competition from the No. 1 group-buying site, LivingSocial recently raised big bucks. Find out how much. It also leveraged its resources to aid recovery from a major natural disaster.
What deals are available: Offers deals in more than 30 U.S. cities.
What makes it unique: HomeRun allows members to earn "credit," its own form of virtual currency, through promoting the site. Credit can be used to make a purchase, and if you earn enough credit by inviting friends to join, you can get a free deal. The "Beginner's Luck" feature gives new members the chance to take advantage of many deals within the first 30 days of joining.
It's getting social: It recently broadened its deal offerings to one of the biggest social media sites.
What deals are available: Features deals in more than 50 U.S. cities.
What makes it unique: SocialBuy also promotes the "group" aspect of group buying. For every friend you refer to the site, you get one SocialPoint. When any friend you send a sign-up link to joins, you earn an additional five points (up to 50 friends per month). You can also earn SocialBucks, which are equal to one U.S. dollar and can be used toward any purchase.
Grocery background: The company was founded by the former vice president of an online grocery service.
What deals are available: Offers deals in more than 50 U.S. cities.
What makes it unique: Not only does Dealster give members a $10 credit for referral, but its coupons are transferable and can be given to others.
Subscribers keep coming: Last fall, the site recorded a growing number of subscribers. Find out how many.
What deals are available: Currently only features deals in its home district but has plans to expand to five to seven major U.S. cities soon.
What makes it unique: Unlike other social buying sites, Deals for Deeds allows customers to select a charitable organization -- from a group of those currently being featured -- to donate 5 percent of the cost of their purchase.
Charities can benefit: One of the first charities that teamed up with Deals for Deeds was an organization dedicated to building affordable housing.
What deals are available: Offers deals for restaurants and eateries in and around six large public universities.
What makes it unique: GrubLife is the first college-focused social buying network created specifically for money-conscious, food-loving students. GrubLife takes advantage of the 18-to-25 crowd's addiction to technology by alerting members of new deals via email or text message.
How good are the deals? A starving college student might be pleased to receive a good deal on their next meal.
What deals are available: Offers deals in 12 major U.S. cities.
What makes it unique: The site does not offer just one deal each day for your city -- it offers three. Tippr features "accelerated deals." It distributes the deals to more than 100 online syndicators, who feature their daily deals on their websites.
Americans love deals: The thriving group-buying industry is expected to have a 138 percent jump in revenue. Find out how much.