Apropos yesterday’s post, this week I bought one of these through the local Apple online store and am loving it - it works fine on my lap, too.
The big advantage for me is that I can use a Portuguese keyboard that is exactly like the ones I use on my desk and my laptop, without any compromises (and without stressing my wrists and fingers on crummy bunched-up keys).
Works with any iPad and any case, and you can also get one here (Amazon US affiliate link).