The Yellow Pages was the Internet of its day
And like the net, it "changed everything."
The Yellow Pages receive billions of dollars in advertising money a year. It's a great business model--businesses show their interest in getting new customers by buying bigger ads than their competition. Consumers choose the businesses with the biggest ads. The Yellow Pages wins.
The other cool thing about the Yellow Pages is that the ads AREthe content. The Yellow Pages without ads don't exist.
Neither one works as a business, but both are a fine start.
The problem is that there's no way for the consumer to tell one provider from another. Distance is fine, but most providers we choose aren't chosen because they're half a mile closer than an alternative.
If you're a search engine, this is the next big thing. (note to Silicon Valley: you'll need thousans of salespeople if you want to do it right).
If you're a business that works locally, this is a bigger deal. Businesses that figured out how to use the Yellow Pages did GREAT (all caps are appropriate here). It was the difference between the big win and just getting by.
So, watch and learn and experiment. Here comes the next big thing.