Play launched in 2007 as a site to help people save money while shopping, then delved into social buying in Hawaii, and is looking to branch out to other states. Play also has a special feature called "prePLAY" in which you gather a group of people to persuade a merchant to give you a deal, though there is no guarantee that a deal will be agreed upon.
Available cities: Honolulu; more locations to come.
Past deals: $25 for $50 worth of food at a diner; $29 for a $55 ticket to Stomp; $35 for two 30-minute Shiatsu sessions ($70 value).
Pricebunch says it features a deal every day that becomes valid once a minimum number of buyers sign on. However, it appears that some deals are featured for longer than one day. Like the Groupon referral incentive, Pricebunch offers a $10 credit to your account when someone you refer to the site completes his or her first purchase.
Available cities: Boston, Chicago, Los Angeles, San Francisco, Washington D.C. Right now, it appears that the Chicago and Los Angeles sites are the only ones with current deals.
Past deals: $20 for $40 worth of cake and pastries; $14 for a whale watch.
Qponus was started in Boston last year, and now offers users a deal everyday. Qponus, too, requires a minimum number of buyers for a deal to be valid. The duration of each deal varies.
Available cities: Boston, Philadelphia.
Past deals: 54% off personal training and evaluation; save 50% on a UV-free airbrush spray tan; 40% off cross-country ski lessons.