Improved approaches to providing on-line appointments over a network are disclosed. The network is, for example, a global computer network such as the Internet. One of the improved approaches provides various notifications to requestors pertaining to appointments with individuals or businesses (e.g., service providers). In one implementation, the notifications can be provided by electronic mail. Another of the improved approaches allows notifications pertaining to requested appointments to be provided to service providers that have not previously registered to receive on-line appointments.