As far as the Kid A / Amnesiac era goes, you could delve a bit into the electronic influences of those albums. Aphex Twin, Boards of Canada, Autechre, etc. If it's just the general weirdness that you like, Scott Walker makes the same sort of "difficult" music.
As far as the earlier stuff goes, well, it seems like the british music press has been trying to find a substitute for the last 5 years at least. You could look through some of those flavors of the week, maybe you'll find something that catches your interest.