Where do you guys usually use Linux (or Unix) at home or at work?
Both! I'm perhaps more Linux-only than most people. I ditched Windows completely in 2000 (booting natively -- I still use the occasional VM), and I'd been dual booting since 1995. Actually, at that time, I had a dedicated 486DX4 "overdrive" 75Mhz machine with Linux -- and before I ditched Windows I alternated between dual-boots and dedicated machines, depending on my current hardware. When I was introduced to Linux, it was at this "computer programming camp" (during the summer, in middle school). Some of the older guys were using it, and I specifically remember wanting to try Linux because I was impressed that you could change the console font. One of the guys was using the "scrawl" font, and somehow that sold me on the concept.
I also use a lot of other open-source and commercial Unixes for various reasons (some just out of curiosity). I especially like to try the ones that require non-x86 architectures.
At work: well currently I'm a CS grad student, and systems is my area of research (operating systems work and distributed systems often in the context of HPC, although before that I did compilers and PL), so I deal with Linux a lot. A lot of OS researchers tend to use Linux as a base for modification. The computers labs here are all dual boot between Linux and Windows. A lot of our infrastructure is run on either Linux or Solaris.
I've worked at various real(TM) jobs (part time and full time in the summer), and we've used Linux in some capacity at all of them. When I worked at the Fed in economic research, all of the HPC clusters to run their simulations were Linux-based. Some of the research economists ran Linux on their desktop too, and all of the IT staff did. Later, I worked at a computer security startup spun out of my school, and everything was Linux-based there. Since we dealt with malware, we had to run Windows in VMs to analyze that stuff, but the infrastructure was all Linux, and most of the developers chose Linux desktops (except for a few OS X guys). Later I worked at IBM and IBM Research, developing filesystem code for Linux and AIX.
Did I mention I'm a longtime member of the local LUG?