Transferring data between systems can be a real pain in the behind, especially if you have data on one and need it on the other. Scythe's Kama Connect is a device that make this transition a little easier. It connects two different drives, including IDE/ATA and SATA hard drives as well as optical drives, to facilitate the data transfer. When hooked up to IDE/ATA drives, the Kama connect doesn't need an external power supply, but when connected to power-hungry SATA drives, you'll need to use the supplied AC adapter. Additionally, it can be connected to a USB port for transfer data to another drive, if you swing that way.
It's pretty clear that something like this would make a great addition to any PC repair center, where customers often come in saying that their "computer is broke." Alternatively, for people who enjoy building their own PCs, it could be a bit of a time saver. At only $29.90, it's probably worth looking into if you do a lot of transferring between drives.