I don't know of any eink device that would support external keyboard. Maybe Kindle 2.0 would work for you, as it has a builtin hardware keyboard and you can take annotations with it, or so I've heard.
HP has a foldable blue-tooth keyboard for my ipaq 214 and I assume you could use that to make annotations in mobipocket reader. But ipaq's not eink based, it has an lcd screen, but there are probably lcd devices with larger screens, if screen size matters to you.
Last edited by Abelturd; 06-18-2009 at 05:05 AM.