I remember I started to use Linux in the early to mid- nineties. Back then home networking equipment was a bit too expensive for me (basically I was student-broke), so I did set up a local network between my "big" Linux desktop computer and my small laptop using PLIP (that is: IP over the parallel line interface IIRC). Then I'd launch an X11 server on the laptop but display on it a session from a user on the desktop. So both my brother and I could surf simultaneously from the "fast" machine. As I remember it things the network was slow, but I clearly remember that it worked. We had our first Internet connection (dial-up) and we were "sharing it" and surfing simultaneously (using Mosaic?) for hours and hours.
Later on I've configured similar setups so that several devs could use older PCs to run fat IDEs from the one fast machine to older PCs (it was funny the day I yanked the power cord of the fast machine, interrupting everybody ; )
Up to this day I still love the fact that it's trivial for one local user (if you allow it) to run programs in the visual X11 session of another user. I'm using several browsers from unrelated user accounts: one only for my personal GMail / Google Docs, one only for browsing, one only for my professional GMail account, etc. That's a feature I use daily and, for my use, I think it's easier (and faster) than running several VMs.
You can also run simultaneously several X11 session, for example at different sizes (say one at 1920x1200, another one at 1280x800, etc.).
I'd really miss these features if they were to go away: I hope the newer Wayland and Mir etc. will still allow one "user" to display graphical apps on the display of another user.
for bandwith reasons, i had a headless VNC X server on the box, and executed X apps locally. Then i'd also start the usual Xserver and client and run a vnc client full screen. So i had the first vnc X server showing on the screen.
then on another box, i had the usual X server+client combo, and i could open a vnc client and have fast remote access and shared screen :)... vnc was much faster than remote X as it only sent input and graphics. X sends all sort of metadata that is not really that useful for most cases.
Later on I've configured similar setups so that several devs could use older PCs to run fat IDEs from the one fast machine to older PCs (it was funny the day I yanked the power cord of the fast machine, interrupting everybody ; )
Up to this day I still love the fact that it's trivial for one local user (if you allow it) to run programs in the visual X11 session of another user. I'm using several browsers from unrelated user accounts: one only for my personal GMail / Google Docs, one only for browsing, one only for my professional GMail account, etc. That's a feature I use daily and, for my use, I think it's easier (and faster) than running several VMs.
You can also run simultaneously several X11 session, for example at different sizes (say one at 1920x1200, another one at 1280x800, etc.).
I'd really miss these features if they were to go away: I hope the newer Wayland and Mir etc. will still allow one "user" to display graphical apps on the display of another user.