I fried my last external hard drive when I plugged the power cord to my printer into it. Consequently, I would like one that will protect me from stupidity. Any suggestions?
A USB powered drive would solve the problem, and you wouldn’t have to worry about power cords.
Also, you can get an external drive enclosure that has the transformer built in, which means that you use the regular computer type power cord rather than one with a AC/DC converter brick in it. For example:

http://www.newegg.com/Product/Product.aspx?Item=N82E16817113012
This is a drive enclosure, not an external drive, but all you would have to do is put in your own hard drive (perhaps even the one inside your old external case still works?) and it becomes an external drive.