1. A method for authenticating a user based on a network-wide reputation for the user, comprising: creating a user account for accessing one or more online services of the network; associating reputation feedback with the user account, said reputation feedback being based on one or more past transactions between the user and at least one of the online services of the network, said reputation feedback indicating whether or not any of the past transactions constitutes a misuse of the network; calculating a reputation score for the user based on the reputation feedback associated with the user account for the past transactions, said reputation score indicating a likelihood of misuse of the network; receiving a request from the user to perform a present transaction with at least one of the online services of the network; and granting the user's request to perform the present transaction based on the calculated reputation score for the user indicating an acceptable likelihood that the present transaction will not constitute a misuse of the network.