simulator

When Pigs Fly is quite possibly the most realistic 3D flying pig simulator

ProPlan is a production planning simulator

Gravit is a gravity simulator.

RC flight simulator for radio controlled planes and helicopters

Bloatware Simulator for testing programs under high system load.

A low-cost, full-feature Verilog simulator. VeriLogger has all the features.

7Edit is a visual HL7 data browser, editor, validator and simulator

A packet decoder, WAN simulator, application profiler

BlueSim is a JSR-82 simulator for compiling & testing JSR-82 applications.

SimSolar - easy to use and entertaining Solar System Simulator for Windows