From Derman Enterprises Incorporated:
KMremoteControl: the cross-platform program that lets you use one system's keyboard/mouse to operate all the PCs and Macs on your desk:
Use your favorite keyboard/mouse for all your work.
Recover your desk space ... hide the extra keyboards, mice and mouse pads.
Control all your PCs and Macs via your favorite PC or Mac.
Avoid buying that KVM switch (for systems on your desk).
Great for laptop users.