On Android there are alternative keyboards available. For Windows 8 I couldn't find any such.
Specifically I'd like to have a keyboard that limits itself to the lower right edge of the screen in order to allow single-thumb-typing, as I do on my phone. This would also largely help on the desktop, where the programs don't work too well with half the screen hidden by a virtual keyboard.
To be fair, even for Android I cannot find THAT kind of keyboard1, so if anyone has an idea for Android - that would also be welcome.
Other alternative keyboards might also help, even if they add just such little things like numbers via press-and-hold of a letter (as used by many keyboards, including the iOS keyboard).
1 I've read swipe supports it for screens larger than 7", but first of all if I'd buy an Android tablet it would would be 7" and second I don't like auto-completion-suggestions, so swype isn't a viable option for me.