Scanners in general? I don't use them a lot but if you noticed the J-card thread at TH then yeah, they are pretty useful. Useful for taking documents and storing them, converting the text in them to store in other files (OCR-optical character recognition), using the images in programs like Photoshop or Corel Draw...
OCR has been around for years. I remember when it became popular, a company called Caere? had the software I always heard about as I seem to recall. Those were the mid-late nineties. Now it's pretty much standard.