New Zealand (South Island)
Seth Kenlon is a UNIX geek, free culture advocate, independent multimedia artist, and D&D nerd. He has worked in the film and computing industry, often at the same time. He is one of the maintainers of the Slackware-based multimedia production project Slackermedia.
Authored Comments
Nothing wrong with TuxGuitar. I'd kinda forgotten about that one, so thanks for reminding me!
Preview.app is not open source, as far as I know :-)
A few of the projects in the comments, like Lightzone, do have OS X versions.