This Teleport software is amazingly useful. It allows you to control two Macs with one keyboard and mouse entirely through software. It even has Rendezvous discovery for quick and painless configuration.
First come across a month or so ago over at the tao of mac, I found a review over at macosxhints and decided to give it a whirl.
Installation was easy, just drag the supplied .prefPane file to a PreferencePanes folder either in /Library or ~/Library (depending on if you want all users on the computer to have access to it). It took two minutes to configure and to my surprise and delight even required authentication when connecting the two machines for the first time.
This is fantastic for me, because it allows me to clear up the clutter of a keyboard/mouse on my work table. I've got a large table with a Powerbook dead-center, an iMac just left-of-center, a television to the right and peripherals to the left. This doesn't leave much room for open books or half-full diet coke cans.
Now my table has some free space and I can control my iMac simply by "throwing" my cursor off the left-edge of my Powerbook. Once I'm better-equipped, I may need to switch to osx2x which has similar functionality, but also lets you control machines with VNC and/or X server running on them. Hot stuff.