An "actor" is itself the unifying pattern for concurrent programming (an asynchronous message queue plus an execution context for processing it), but there are many design patterns which assist in specifying aspects or elements of agent-based systems. Many of the most common can be found in Wikipedia's article on Concurrency Patterns. Some highlights:
- Reactor Pattern
- Mediator Pattern
- Scheduler Pattern
- Observer Pattern
If you haven't come across it already, Akka may be of interest to you -- it is a "purely" event-driven actor framework running on the JVM.
