Codeplex

Codeplex is like a big toy box where people who know how to write computer programs can put their toys for others to play with. But instead of actual toys, they put their computer programs in there for other people to see and use. It's a place where programmers can work together to make really cool and useful things that anyone can download and use for free. It's kind of like a huge playroom where everyone can share their toys for others to enjoy.