External hard drives
These can be useful if you're short of disc space on your computer. They can also be used for backup.

CD and DVD burners
These are useful for distribution and for backup. Some computers come with these built-in.

Screens and monitors
Complex professional programs are easier to use if your computer has a large screen. It can also be useful to connect a TV monitor to the analogue output of your camera or deck so that you can see the image at full quality as you edit.

miniDV deck
Using a separate DV deck for editing saves wear on your camcorder and means that it's not tied up when people are editing. However, it would usually be cheaper to buy another camcorder.