I remember someone telling about this nice exercise do develop KI.
Form a circle of people each one holding a bokken (it's easier to project KI through the tip of the bokken). In the center of this circle there will be a blind folded aikidoka. One of the Aikidokas of the circle must point the bokken to the person in the middle and try to expand KI like if he/she were going to attack while the other people of the circle keep the bokken down. It's said that it is a good exercise to develop the ability to sense KI from other people.
I've never tried though! But it seems interesting.