Two places:
1) The two I use most often (a #5 and #3, both Stanley) live on the shelf of my workbench just below the top, along with a Ward's Master #4 and a 24" transitional, probably made by Siegley. They share the space with a few other things.
2) The rest go in an old wooden toolbox I inherited from my grandfather. That collection is a couple of block planes, a #78, a Sargent-made Craftsman combination plane, and a couple of wooden planes of various types.
I'm in the process of building a Dutch-style toolchest, since that's what will fit in my winter workspace (though I would LOVE to have space for a full size English joiner's chest...), and once I have that and a base cabinet built, everything should fit in the two.