I like GraniteDigital.com's offerings. They have hot swap cases, so you have a few drives in caddies/trays and swap them in the main enclosure. I've got two 80GB and a 120GB drive in mine and they're great. Especially if you need a lot of storage. The main case is around $200 and the trays are $30, but it's cheaper than buying another $100 full size case every time you need to expand. Plus, if you were to have enclosures in different places, moving the drives in the caddies works out really well.
They've got FireWire 400 and 800, USB 1.1/2 and regular (non-hotswap) cases.
cpjakes