With the exception of the occasional mower, house ****, or very occasional Harley, everything I work on is all metric.
I have a drawer at the bottom of one of my toolboxes that is the designated "inch ghetto". All the nearly useless inch **** gets tossed in there willy nilly -- it's not worth any effort to keep it organized. I have a smaller drawer where all the inch **** fasteners get tossed in so they don't contaminate my nice neat drawers of metric stuff.
Most of the motorcycles and cars I work on are Japanese, so I also separate my metric stuff into the JIS stuff (8, 10, 12, 14, 17, 19, 21, 22, 24mm, etc.) and put the stuff you only encounter on 'merkin and Euro cars (9, 11, 13, 15, 16, 18, 20mm, etc.) on a second rail in the back. Saves a good bit of time when you don't even have to look to grab the right socket or wrench.