If you're into the 2.5 inch hard drive scene, as in you have a number of them available and you need to port them around for some reason, this portable drive case from OWC seems like a pretty good idea: it's got an aluminum heat sink on the bottom and pass-through vents on the top to keep things cool and both USB 2.0 and eSATA connections for greater compatibility, all in what looks like a hard plastic case. That said, since the manufacturer aims the product at Mac Powerbook users, I'm not sure why two types of connections are necessary - Mac seems to be pretty standard about the connections it includes.

Via Macworld