My Mom uses Ubuntu
I don't quite know how it happened, but my parents finally got the Internet / computing bug. Last year, my Dad bought a Dell Studio and my Mom bought an HP Mini. For the longest time, they went largely underused -- my Dad used his to play pinball, and my Mom, well, she hasn't been using hers at all. For the most part, the HP Mini fell into my hands.
But not anymore. Slowly, my two senior citizens have been getting the hang of things. My Dad has moved up to web browsing and photo management, and he's added Chromium BSU to his game repertoire. He's using Windows Vista, though, so his story isn't of much interest here (the Dell Studio came with the operating system, so it felt like a waste to wipe it out.)