Considering how many ways there are to move files back and forth between Macs, it seems almost comical that anybody complained when Apple discontinued built-in floppy disk drives. For one thing, you can almost always email the file to someone— even to yourself! And there are plenty of other ways to move files around.
With about $50 worth of equipment (or $200, if you want to go wireless), you can connect your Macs together into a network. Once you've done so, you can keep an icon for each Mac's hard drive on your screen. You can open files from the other drives, copy stuff back and forth—anything you would do with your own disk.
Step-by-step instructions are in Chapter 13.
You can always burn your files onto a blank CD or DVD and then carry it to the other machine. You'd use this approach when, for example, you have a lot of data to copy, but the two Macs aren't within networking range; for example, they're not in the same room or the same city.
FireWire Disk Mode is a brilliant but little-known, Macintosh-only feature that lets you turn one Mac into an external hard drive for another. This is by far the fastest method yet for transferring a lot of data—even faster than copying files over a network. It's extremely useful in any of these situations:
You're traveling with a laptop. You want to copy your life onto it from your main Mac, including your entire 2 GB email folder and project files, before ...