I just got the keyboard/case thing from Logitech
. You can find it for ~$30-40 on eBay regularly.
I've only used it about a day, and only at home. Check back here in a couple of days to see if it's survived the office. So far I can tell that the tablet fits snugly and won't fall out or pop out, and it isn't overly hard to put it in or take it out. It exposes the back, but it does protect the screen really well. BT pairing is solid, and the keys are surprisingly nice. Application -> key mapping is sane, especially for a vim & screen user. The aluminum base is pretty thick and I don't see it deforming much even if you drop it. The charging cable is far too short, but it uses microUSB, which most everyone here should have a spare for. One nice touch is the cutout at the back for the dock connector so you can charge while the case is closed.
I've been needing something netbook-ish, but don't usually need more than a terminal and a browser. I don't want to spend $$$ on a Transformer just to get a keyboard, and a notebook with this sort of battery life and screen quality would near $1k. Along with AirTerm (and AIDE once I get around to developing apps) I'm hoping this combo will get me through the next upgrade cycle or two.
I can't speak firsthand about the unbranded one you've linked to, but the Amazon reviews for that style tend to be pretty bad, with pairing reliability and the Tab not staying seated being the biggest common complaints. And that's saying a lot since many of those white box accessory vendors reward customers for good reviews.