I was reading an article by Mike Mahler in the achives looking for kettlebell exercises and I saw a picture of him doing dumbbell shoulder presses sitting on the ground. It generated some dicussion after the article and he said that it helped focus on the shoulders and prevented arching.
I tried it out during my last workout and I have to say it was humbling. Normally I would use 50 lb dumbbells and 10 reps would be easy. I had to go down to 30 lb dumbbells and it was pretty tough. On the following sets I could only complete 9 and then 8 reps.
Since there's a smaller chance to cheat it's probably not a good exercise to go heavy on but it makes a good accessory lift.