Pico Genie have recently released their smallest entry to the portable pocket projector category, the P50. The new unit is the smallest in the world at 40 lumens with a 2 hour inbuilt battery (projecting at full brightness) with an extensive range of connection options.
"Next time you're away on work, pack this 148g projector, which can create a 60-inch cinema screens on a wall. The P50 connects to almost any computer or smartphone."
Quote source: GQ Magazine