[ashark]

You mean the stackable dog bone-shaped ones? They don't look that big to me, but maybe the pictures don't do them justice.

I'm not sure whether it'd be appropriate for what you want, but this is the case I bought:

http://www.amazon.com/dp/B00ME5XUAG/

I'm happy with it, and I can't really imagine a case being any smaller and still protecting the Pi while providing access to its various ports (including the SD card). I'm not really into the see-through case thing, but I couldn't find an opaque case I liked better for the same amount of money or less.

[kolev]

I mean something like this [0], but more efficient as you need an outer enclosure only. Blade-server like would be idea (where the Pis are vertical) with some more efficient Ethernet cabling to connect them to a switch.

[0] http://www.amazon.com/gp/product/B00MYFAAPO/?tag=nikolay-20