GeoGebra for the iPad

It is already a great program (CAS, graphing, spreadsheet, soon 3D graphing) for K-14 mathematics exploration on computers. But its move away from Java to html5 and beyond could make it into a superstar in mathematics education.

The idea of exploring visual mathematics by just dragging points around makes me wish I were young again.

I also wonder whether this funding model may become more common for useful apps--fundraise, get your money, make a great product with minimal risk though with minimal gain.