We have talked about the Eye-fi wireless SD card before, and a quick Google search shows that it has quickly caught on with the digital photography crowd. Even better is the fact that the new Niko D90 that everyone is so excited about is actually designed to work with the Eye-fi card as though it came with it in the box.
From digitalbear's Flickr
Not only does it make sure that the battery stays on as long as there is a wireless upload happening, you also get Eye-Fi specific menu controls on your Nikon D90 so that you can turn the wireless function on and off for situations where you shouldn't be blasting a signal. All the convenience without the cords and you save the hassle of sitting down to dump all the images off your memory card.