Here is a video of a ducted fan hexacopter, looks kinda cool, dont know if I like the sound too much 
, or maybe its just my speakers.
Although the design is nice because its compact, the power ducted fan motors produce lots of thrust but also use a whole lot of battery. This setup has a flight time of 9 minutes and uses 16.8Ah (4x 4200mah) with a total takeoff weight of 3.5Kg However still fun to see!