Not in a roguelike, but in a few other games I've worked on, the hex grid is basically just a skewed square grid - the Y axis is up and down as normal, but the X axis goes off at a 60 degree angle to the right, instead of a 90 degree angle. (Sometimes we consider a third axis called "Z" which goes off at a 60 degree angle to the left, say, for purposes of computing bounding hexes, but strinctly speaking, any hex position can be described in terms of X and Y; Z is redundant.)