Unfortunately the Boards of Canada don't have much at the moment, only three albums and a few EPS. I reckon it's because they spend forever carefully crafting their sound (just look at the Geogaddi section of
http://fredd-e.narfum.org/boc/info/ to see what I mean), but in any case Geogaddi and Music Has the Right to Children are their two best albums, and In a Beautiful Place... their best EP. But Twoism and Hi-Scores, two of their earlier EPs, are also good listens. The thing about them is that their sound hasn't changed much at all.
