We've seen the prototypes that led Google to Glass, but there are many devices that predate Mountain View's smart specs, and Augmented World Expo in Santa Clara, California was able to gather and display a historic number of such headsets this week. From Steve Mann's handmade WearComp 1 and EyeTap prototypes to Glass-like precursors from Optinvent and Vuzix, it's quite the comprehensive collection -- over thirty devices in all. While they may make their way into a museum some day, we're bringing pictures of them all to your screen right now. Enjoy.