Thanks to Synergy, my Slackware Linux and Windows XP boxes share a keyboard and mouse. I have my BitchX window & instant messanger on the monitor that's connected to the slackware box (as well as a firefox window, however, that is not the firefox window I'm looking at now.)
I also have an SSH session to my OpenBSD Laptop (on my slackware 11 box).
I also have an SSH session to my HTPC running Knoppmyth (on the slackware 11 box)
I also have FreeBSD, OpenBSD, and ArchLinux Virtual machines running on my Windows XP PC ... I've been experimenting a bit.
So, I'm not quite sure how to answer this poll, as I am not running just one OS. I have tasks divived up between multiple boxes, everything is totally accessible from the keyboard and mouse connected to my XP box.