I've spent several decades giving away software of one sort or another — which was generally a lot more fun than selling it :-)
In recent years projects I've founded have been used by organisations as diverse as the BBC (for their 2012 Olympics website), the Health Protection Agency (for research into producing vaccines more quickly), or the NHS (for analysing patient records).
You'll find the results on GitLab, on SourceForge, on GitHub, on Ubuntu Launchpad, and from the Sheffield Pi-Tronics and GATE sites.
Next up? Moving from open source software into open hardware — like this Raspberry Pi mobile power add-on. Warning: this obsession can be contagious, particularly if you read one of these:
- Makers, by Cory Doctorow [science fiction]
- Makers [yes, same title!], by Chris Anderson [non-fiction]
- From Zero to Maker by David Lang [non-fiction]
If you haven't already got one, now go out and buy a Raspberry Pi and/or an Arduino, and live happily ever after (probably).