I soak them in an ice chest. It does keep the water hot even overnight. And the cooler comes out whiter too after a good oxy soak. I use a cooler with a flat bottom, my bigger one has a drain channel in the bottom that makes it hard to stand the bottles up.
This may be a dumb question...
I'm thinking of taking up kegging instead of bottling, and while I like a project as much as anyone, the keg will probably have to go into the existing garage fridge at first. This fridge is currently used for beer in bottles, but also other drinks and overflow...