UMBC KQML
Information and resources for the Knowledge Query Manipulation Language (KQML)

J.Agentx
A portable, lightweight implementation of the AgentX protocol for SNMP Agent Extensibility. This Java-based package was developed at the University of Coimbra, Portugal. [Freeware]

Agent Communication: Needs and solutions - The Web Developer's Journal
This article presents an overview of the need for agent communication, and possible solutions.

Simple Agent Communication Protocol
An easier approach to agent communication. Presentation of David Reilly.