Microsoft is giving its users an opportunity to direct where its charitable efforts go to through the i'm Initiative, which sends a portion of Windows Live Messenger ad revenue to a selected charity.

In order for the effort to work, a user must add a special code to the end of their display name that would then be tracked. The more often a user sends instant messages, the more Microsoft donates to that charity.

Users would need to have Windows Live Messenger 8.1 and reside in the United States to participate, however messages to overseas friends would still count. Each participating group would receive a minimum of $100,000 per year, the company said.

"Not everyone has the financial ability to give money to the causes they care about," the Windows Live Messenger team said on its blog Thursday. "That is where the i'm Initiative steps in - it enables Windows Live Messenger users to make a difference by directing a portion of Messenger's advertising revenue to a cause of their choosing."

Participating charities include the American Red Cross, National AIDS Fund, the Sierra Club, stopglobalwarming.org, and UNICEF among others. An icon "i'm" -- short for "I'm making a difference -- would appear alongside the display name of users participating in the initiative.

Only one cause can be supported at a time, although the company says users can switch between charities as often as they'd like. More information is available from the official i'm Initiative Web site.