Citi is giving its customers a chance to share or combine ThankYou Rewards through a Facebook application. ThankYou members can combine points to make a charitable donations or choose from rewards. Citi says this gives members a chance to help their friends get a bigger reward or support a common cause.

To kick this off, Citi is giving away 10 million ThankYou points to qualifying ThankYou members on Facebook. The first 4,000 ThankYou members to like the ThankYou Point Sharing App to their personal Facebook page will receive 2,500 ThankYou points from Citi. Individuals must be a Citi ThankYou Rewards member.

The Citi ThankYou Point Sharing App allows you to start a pool of points for an individual, group, or cause and set a goal and track the donations. Facebook friends who are ThankYou members can join the pool. This includes people with a Citi credit card with ThankYou Rewards or a Citibank checking account with ThankYou Rewards.

If you don’t have a plan for your points, or don’t accumulate enough to cash in, this can be a good way to use the points to help a charity or do something nice to someone you care about. Keep in mind that this is also a smart move by Citi to build loyalty and give you another reason to use your Citi card. If you carry a balance on your Citi card, your biggest concern should be paying off your balance instead of earning more ThankYou points.