Whatever Happened to Nancy Drew?

Where have the heroes of childhood novels gone? Nancy Drew, Tom Swift and His Electric Widget Gun, and the Hardy Boys? Have they disappeared, or did they just fall off my radar as I grew older (and started reading Heinlein, Anderson, Simak, et al)?

To fill this void, the Japanese (who else?) have a new TV series called Keitai Deka, which means "The Cell Phone Detective". It's about a teenage schoolgirl who solves crimes with the help of her trusty cameraphone. No more human sidekicks, I guess.