Dating services are second only to the porn industry for paid Web content. Until this year, revenues for some of the largest dating services were doubling each year. But all of that is starting to change. Growth has slowed dramatically, and workers are being laid off. The question is why? Isn't the demand for meeting people the same? Are people going back to the old fashioned way of dating? According to the article in the link above, part of the reason is because the novelty has worn off. In economic terms one could say that the marginal utility of using online dating services for some customers has reached 0 (or less). But the change is also due to substitute products. Mobile devices are taking the place of online dating services. Text-messaging services have sprouted up in San Francisco as well as cell phone services that alert a user when a "friend" from the service is in close proximity. The newer services are also doing a better job of matching people with similar interests in chat rooms. I guess you could say the marginal utility for using the new services is higher for some customers for using the new services than it is for the using older online dating services.