

The Polynesian people had many ways of detecting land far beyond the horizon using ocean currents, temperatures, weather patterns, animal movements, and others which they used to island hop all the way through the Pacific Islands.
I have little doubt it was a well informed theory before they got into their vessels.
Audio mixing, Photoshop, Blender, CAD, etc.
Lots of creative applications.
FWIW, Ploopy is a massive force in the open source hardware game. Mice, trackballs (their specialty), headphones, and lots of other items.