This document summarizes a survey on the Sensor Protocol for Information via Negotiation (SPIN) routing protocol for wireless sensor networks. It begins with an introduction to wireless sensor networks and describes the basic operation of the SPIN protocol. It then discusses several extensions and improvements made to the SPIN protocol, including M-SPIN, SPIN-pi, and SPIN-I, noting problems or limitations with each. It proposes a new solution that combines the M-SPIN protocol with the use of "plug-in" nodes to improve reliability and network lifetime. The proposed solution is described along with an algorithm and network topology. The document concludes by acknowledging references used in the survey.