The major sellers were the Hula Hoop and the Rubik's Cube in the '50s and '80s, respectively. One thing that is for sure, teen-agers have gone from longing to stay children in the past to their current yearning for adulthood. This is apparent by the change in popular gifts throughout time. Teens tend to shy away from clothing that mimics the style of their grandparents. Bright colors and fleece clothes are among the most popular styles that teen-agers prefer.
Books also seem to make boring and unexciting gifts.
With society moving toward computers in everything way, it isn't surprising that PCs along with games and various software often appears on the wish list. There are always those who shy away from the ordinary, though. The changing form of gifts can be identified by the personality of those receiving the gifts. But beware, gift givers. This generalization is always going to have its outliers who don't follow certain trends.