It's not where you meet but whom you meet that counts.
The same people you meet online go to the grocery store, beach, movies, parks, gyms, malls, nightclubs, church, and any other place you would normally meet someone. As Shelia Lee alluded to not all dating sites are equal. Oftentimes it's a case of getting what you pay for concerning quality of people.
According to some reports 1 in 5 marriages today takes place between people that met online. I suspect that number will rise significantly over the next 10-15 years. Much like the fear of using a credit card to make online purchases several years ago...etc People eventually embrace modern technology. Having said that (meeting a stranger has always come with risk). It's very important to use good commonsense.
People are too quick to trust people they are "attracted" to. Trust like respect should be earned overtime. I have had relationships with people I've met online that lasted up to 7 years.
Awhile back I wrote a hub offering some advice regarding dating websites.