At home and office
I use different systems.
At home, I typically use OS X. For my job, I need to use Windows [word/Excel] and Linux [deployment target].
Apple Boot camp is OK, but booting to swtich OSes isn't an option for me.
Thus, I'll use parallels WS to make my business apps available at home - and keep my noisy PC off ;-)
Moreover, I'll use parallels WS to run certain Linux system configurations and test certain stuff. MOving VM images from home to office is a nice option too.
Great work, folks!
PS: Do you (partly) use any of those hypervisors like XEN in your solution?