Universal ledger

An obligation tracking system communicatively coupled with one or more social network services that provide social networking between individuals, the obligation tracking system being configured to perform the following operations:

• receiving a request from a first user of a first social network service, wherein the request comprises an expense incurred by the first user on behalf of a second user of a second social network service, wherein the first and second social network services are different social network services that each provide non-financial services to users;
• providing a notice of the request to the second user;
• receiving, from the second user, a confirmation that:
• the item or service was purchased on behalf of the second user;
• and
• the second user will assume an obligation associated with the expense, wherein the obligation is substantially equal in value to the expense;
• associating the obligation with the second user in response to receipt of the confirmation;
• associating a benefit with the first user in response to receipt of the confirmation, wherein the benefit is substantially equal in value to the expense;
• providing the first social network service with information about the benefit;
• providing the second social network service with information about the obligation;
• receiving a settlement from the second user to satisfy at least a portion of the obligation;
• providing the settlement to the first user;
• and
• providing the first social network service and the second social network service with information about the settlement.