The most intuitive way to build a service directory application that allows for service entities to register or search for services on top of a structured peer-to-peer network is to build reverse indices at appropriate nodes on the network. However, this implies trust on the reliability and integrity of other nodes on the network, which may be too risky an assumption for businesses. This paper proposes a service directory that groups service entities of the same category together; this is achieved by dedicating part of the node identifiers to correspond to their service category semantic. Using Chord as the peer-to-peer substrate, this scheme logically divides the Chord circle into equidistant arcs; each arc is called an island. This scheme will result in the formation of islands of varying population, and thus changing the uniformly spread topology of the original Chord. Simulations are used to investigate the path length and message load of the changed topology. An additional routing scheme is also proposed and simulated to exploit the new topology to gain better path length.