Muxtronics @ tindie.com sells their 4-port NanoHub board:
The NanoHub 4-port is a natural evolution of the original 2-port NanoHub – a truly tiny USB hub to use in the most cramped of spaces. Nanohub 4-port is bigger and better! Even though it boasts twice as many downstream ports (effectively tripling its usefulness; providing 3 extra USB ports instead of just 1), it is only 4mm wider (1/8″). Also, by popular request, ESD protection diodes are included on the input and output ports, meaning you can safely use the NanoHub 4-port with user-accessible ports, where you might zap the port contacts with static electricity. Lastly, the power traces have gotten a slight boost; you can now draw up to 4A on the output ports (combined, sustained).
4-port NanoHub – tiny USB hub for hacking projects – [Link]