You could look at one of the Epson views P-3000, P-4000, P-5000...etc. They're great little units, compact and have good screens on them. They are however NOT cheap. Easily found at Adorama or B&H etc, and I'm sure you could look around for the best price. They take most card formats and depending on which unit you get have decent sized hard drives. I use mine as a backup for location shoots when I don't want to lug around my laptop. Only real complaint I have is the price.
Epson Digital Photography - Epson America, Inc.
There are other manufactures out there, but I can only speak to the Epson as it is the only one I've ever owned.