The Gamepark Holdings GP2X: The little open-source handheld that could

When GamePark split after releasing the GP32 one half of the company went on to produce a wannabe PSP competitor, but the other decided to make a cheaper iterative improvement over the original. They created the GP2X, a fantastically successful open source homebrew and emulation machine.

GP2X software is still available here https://dl.openhandhelds.org/cgi-bin/gp2x.cgi