I have a 9600/300 that I would love to put back into use for something. Just one problem - I only have room for one monitor and it's already connected to a 4-port PS/2 KVM switch for my PC and my Blue & White G3. What I was thinking was to add an USB card to it, connect one of the KVM cables to it with a PS/2 to USB adapter, leave the ADB keyboard connected and see if that would allow me to use it with the switch.
With the Blue & White G3, I have one of the KVM cables connected to a PS/2 to USB adapter and that is plugged into one of the USB ports. It works okay on that, but it's hard to remember to use the Windows key for the Apple key. 
Any suggestions as to the workability of this?
I used a beige G3 on a similar setup, and it worked okay. Only setback is you won't be able to use the PS/2 keyboard and mouse until the USB extension loads.
If you intend to keep an ADB keyboard, that gives you access prior to that extension loading. Should be no problems.
The Belkin Omniview PS/2 to Mac adapter works pretty well for me with an old Omnicube 4 port KVM and an 8600. Overall I'm not too impressed by the compatibility of later Belkin KVMs with some very standard PC hardware, so don't take this as a global recommendation. MacIntouch has some good info on KVMs for ADB Macs and Suns.
Currently I'm using a Zonet KVM switch. The switch came with 4 cables and was about $40-50. So far I haven't found anything that doesn't work with it.
I picked up a generic USB-PS/2 adapter this afternoon for about $8 that I know works with a B/W G3. If it doesn't work here I have one of those legacy-free Compaq iPaq computers at work.