Take the fans off, and lay them down sideways, flat ends together. We used some cheap plastic pieces of wire conduit, and laid out channels for them to sit in so they don't roll sideways. Blow a small amount of air down the row, and heat isn't a problem at all. Cable management is also somewhat easy, as all the power and data are running the same direction.
Ends up with a very nice setup, and on our 2x4' shelf, we estimate we could fit close to 150 units.
Of course, if this is too much, I do believe they are working on 5 and 10MH/s standalone units, but last time I checked the price was more expensive than just buying the little round ones and chaining them together....
