A wide-area service discovery infrastructure provides a repository in which services over a wide area can register themselves and clients everywhere can inquire about them. We discuss how to build such an infrastructure based on the peer-to-peer model. The proposed system, called Neuron, can be executed on top of a set of federated nodes across the global network and aggregate their resources to provide the discovery service. Neuron is self-organizing, self-tuning, and capable of tolerating failures of nodes and communication links. In addition, it allows the services to be described with arbitrary forms and the system load to be distributed evenly to the nodes. Neuron also supports event notification. We evaluated Neuron via simulation. The preliminary results show that service registration, discovery and service state advertising take at most O(log N) hops to complete.