If you take a lot of digital pictures (I have 7000 images on my laptop right now, and lots more archived), you spend lots of time copying files across to your computer. Most cameras come with USB cables, which aren't really that useful.

My preferred solution is a CompactFlash PCCard adapter. You take the compact flash out, plug it into the adapter, and slide the adapter into your laptop. At that point, it looks just like a disk drive, as compactflash cards look like IDE drives. Easily copy the files across and delete the existing ones, without having to use camera power. It's also a bit faster.

You can also get these for other storage formats.