I picked up this recipe from Food Network's website. I don't really care to watch anything with Paula Deen in it (although I do like her use of butter), but this was the best hamburger I've ever made.
1.5 pounds ground beef, 80% lean
1/2 cup cold water
Salt and Pepper
Mix everything together. Form into hamburgers with a hamburger press. Cook 8 to 10 minutes per side for medium-well done. The water makes them stay extremely juicy.
My one modification to this is that instead of just putting water in, I first mixed the water with a brown gravy mix for extra flavor.