You know it: keyboard or mouse input is just too mainstream to create Random Numbers through human behavior.
Create the most unique (Pseudo)Random Number Generator that create its numbers through human behavior.
Web-API's are not restricted! Anyone should use the code provided, so any special hardware is restricted. (I think we can assume that everyone has a smartphone) The number should be a 256 bit number.
Example: use the Google Map's API to get current traffic to create the Random Number.
This is a popularity-contest, so most votes wins!