Ketttlebell Shoulder (Seated) Press
Sit down on the ground with your legs straight (but knees not locked) and splayed out a little. Place the kettlebell on the ground between your thighs.
Grab the bell's handle with one hand and clean it (bring it to shoulder height, with the ball resting aginst the top of your forearm). As a second movement, press it directly up until your arm is straight. Keep looking straight ahead throughout the press.
Reverse the two movements (bring the bell all the way to the ground), and repeat.
As with the Kettlebell Floor Press, this can be performed with one or two kettlebells; either in unison or alternately. It can also be done standing as a Military Press, or seated on the end of a bench.
As you've probably guessed, there is a slight tendency to tip over backwards when doing these. This is overcome by flexing abs and glutes, which is why there is a different feeling between the seated and standing versions of this exercise.
Another thing which increases stability is holding your breath during the press.