Warehouse clubs were first.  You paid a membership fee and got amazing discounts on large bulk purchases that you made.
Then came group action for good.  Kiva lets you select a microloan recipient across the globe who appeals to you and whose business you can help to finance for as little as $25.   The Point lets you either start a fundraising cause and invite people to support you, or you can add your dollars to an existing cause.

Now group buying.  Groupon, eSwarm, BuyWithMe, GroupBuyers.ca and the like—offer ways to either just share deals in your area on a board, through actually tracking deals for groups of buyers, online.

We found the newest take on group buying at Springwise.com, called SyncFu.  Taking advantage of the Web 2.0 social, smart-tech use, SyncFu offers an embeddable widget to online retailers.  The difference here is that SyncFu allows many individual buyers to directly contact and get discounts from the people selling the products.

The more people who say yes to a group purchase, the more the discount can be.  Other online group selling funnels purchases through a third party.  Less work for the seller, but also up to 50% less money for them—the third party takes the commission.

To join a group buying offer, customers just click on the “Join Group Buy” button on the seller’s website. Then the SyncFu widget tells the buyer how the price drops as the size of the buying group grows. If interested, the customer leaves his or her email address and makes a micro-payment of less than $2 by cellphone or credit card.

They can also spread the word about the deal, in the hopes of increasing the group size and lowering the price. SyncFu, meanwhile, gives each pledging buyer a code to get the discount when buying the product.

At the end of the deadline, all buyers pay the most recently listed low price. Since the deal is done directly in the seller’s web shop, there are no intermediaries so sellers keep all the profits.

Great news for buyers and e-commerce site owners alike!