I came across two cool projects on github recently. The first is the sourcecode for the Apollo 11 command module and the lunar module. Apollo 11 made its historic trip to the moon in 1969. Neil Armstrong and Buz Aldrin landed the lunar module; Milchael Collins piloted the command module. The code is a flavor of assembly language and while it is pretty cryptic it is sprinkled with lots of comments, and if you read it carefully you can find some jokes and comments about the times.
The second software project released to github is PhotoShop v1.0
While modern releases of PhotoShop are written in C++, this early version is written is Pascal. Really coold stuff though, and really well written code for so long ago.