Hey Linux users, if you plug in a second mouse, you can turn it into a second mouse pointer pretty easily:

    xinput create-master "Second"
    xinput list
    xinput reattach [device id] "Second pointer"

where [device id] is the mouse hardware device listed in `xinput list`. See https://wiki.archlinux.org/index.php/Multi-pointer_X for more information. (You can also get a second keyboard focus this way if you plug in a second keyboard; see the link for details.)

This is only tangentially related since it doesn't do the "screen sharing over a network" thing, but it can be handy for pair programming on a huge monitor.