As a tween/teen, I learnt a lot from OS/2. Up until then I had only used DOS and Windows 3.x. And then my Dad bought me a copy of OS/2 2.0, and also the Walnut Creek Hobbes OS/2 CD-ROM. And I discovered EMX (the OS/2 equivalent of Cygwin). And I started playing with bash, EMACS, GCC, etc. Next thing you know, I was installing Slackware Linux. At which point I largely lost interest in OS/2. But EMX was an important stepping-stone for me in getting in to Linux.