TTIP, or the Techinc Tower of Insane Power
Inspired by this: http://hackaday.com/2015/07/08/insane-33-port-usb-charger/
I thought it can easily be made bigger by building it vertically, making every level of two piggybacked USB chargers, and mirroring them on the odd levels.
Every inch height will then be ~2 adapters, so 8 pieces per 10 cm. A tower of 50cm would be quite doable, but the challenge lies of course in making a tower of say 100cm or higher.
I know someone who purportedly has a LOT of these adapters he can donate towards this project...