FSX Traffic Generator is a tool designed to generate more less realistic AI traffic in Microsoft Flight Simulator X. It's developed in C# using Visual C# 2008 Express. FSX Traffic Generator generates DAT files (that can be easly transformed into BGL files) from RDL files.
Result (FSX screenshot):
More information at: http://fsxtrafficgenerator.codeplex.com/
You can download this application from: http://fsxtrafficgenerator.codeplex.com/Release/ProjectReleases.aspx (ClickOnce installer)