I found something in a Black & Decker Home Maintenance book that works for me -- combine 1 cup of table salt, 1 cup of banking soda and 1/4 cup of cream of tartar. Put a scoop of it (I use about 2 tablespoons or so) in the drain and then add two cups of boiling water. It does sort of a fizzing thing, and when I first did it, there was sort of a muffled "poof" and then all of a sudden the water started running through, so I assume that was a soap glob being dissolved or something. Anyway, I do that once a week, and haven't had drain problems since. For hair, I just manually pull out the shower drain and remove it every couple of weeks.