I've used my BlacX duet so much it's ridiculous. Only real flaw is the way E-SATA connection behaves in single slot mode on some PCs, but overall my favorite disk appliance short of my Rocketraid 8 port SATA/SAS disk controller.
I have a handful of 90GB Corsair Force disks I am very happy with, as well as a nice older SATA II model of that Samsung disk up there that's so popular.