I am sure that there are tons of people out there that have old 2.5-inch or 3.5-inch HDDs lying around that are doing nothing other than collecting dust. Those drives are probably still good and you just don't want to trash them. Trendnet has a couple new external HDD enclosures that will let you take those old drives and make blazing fast external storage out of them. The new enclosures include the Trendnet TU3-S35 and the TU3-S25.
The two enclosures have the same features with one notable exception. The S35 supports 3.5-inch SATA I or II HDDs and the S25 supports only 2.5-inch SATA I and II HDDs. Both of the enclosures connect directly to the USB 3.0 port offering up to 5Gbps of transfer speed. The enclosures will support drives with up to 1TB or more of storage space.