This may sound "anal", but I hang the rulers that I use ALL of the time on the wall by my cutting table.
For rulers that I rarely use? I use hanging files with a tab for what EACH ruler is (I do group square rulers, 60 degree rulers, etc)...but everything else is in its own file....I keep these in one of those smaller, portable see thru plastic files with a cover...and sit it on a shelf in my closet...easy to grab the whole thing and find the ruler I want...it works for me
Some larger specialty rulers still need to be hung up.