I too use milk crates. They stack perfectly and I only need two for one five gallon batch. I find they hold 25 standard 12oz bottles.
Someone on the board found out that legal sized file cabinets fit 12oz six packs perfectly. Score some of those on craigslist and you're golden.
Edited to add:
found the link: http://www.homebrewtalk.com/f11/my-n...ge-unit-90478/