Mick Curran and Jamie Teh are lifelong friends who share a love of music and technology. They're also blind. Both computer programmers, the pair saw an injustice they wanted to fix: vision-impaired people have to buy expensive screen-reading software to access computers and the online world. Their screen-reader is now used across 175 countries and has been translated into 50 languages. And despite the potential to cash in on their innovation, they've kept it free for all.