as most have mentioned, it's just a matter of being considerate. i'm not a big person, so it never bothers me when someone reclines. that being said, i always think they're *****. i many recline just a hair for my back's sake, but like just jack mentioned, it's only so i'm not sitting straight up.
i've had good luck lately on planes with people around me. we've taken small kids on flights, and other passengers have been helpful, understanding, and even complimentary. one lady even offered to watch my daughter while we took things off the plane. it goes both ways. on another flight when i was by myself, i had an isle in a three seat row. one guy was in the window seat and the middle was open. sure enough a guy who was in the 6'3"-6'4" range, with a broken leg, on crutches, was our middle seat friend. i wasn't going to make that guy sit in the middle, so i offered him my seat. with the look of gratitude he gave me, you would have thought I offered him my wife.