StanD:
I have used a shift register to control a character LCD with only three Arduino pins:
Arduino controlled LCD using a shift register and the SPI library – 42 BotsSo, definitely good for more than LEDs...
Specialized ones have additional applications, though I think the thread is mostly talking about the general purpose and cheapo shift registers. For example, most VFD drivers are simply high voltage shift registers. Here are two I have used with no problems:
MAX6921 (20 output, 76 volts)
PT6306 (64 outputs, 70 volts)
The second one is both a lot cheaper than the Maxim part and also has three times the outputs. It works great for displays with a large number of grids and segments.
Don't lick the project board when running it at 70 volts. 