In gaming: all of the idTech engines, the Unreal engine, and so forth. Unix was an internal tool at Bell Labs, as was C. Rails was pretty much just a framewor

In gaming: all of the idTech engines, the Unreal engine, and so forth. Unix was an internal tool at Bell Labs, as was C. Rails was pretty much just a framework over at 37signals before it spread. ~ This happens a lot in software.