A few weeks ago I open instructions again for my new build and I found that a discrete DONATE button appears without any announces so, if someone that want to contribute with developers but is not reading instructions, now the button is there :) ; perhaps it's a good idea to have another in support forum?

http://copter.ardupilot.org/ardupilot/index.html

Little amount from many people = big amount to continue support developers, for continue enjoying this great hobby :)