Online dating is big business, and they spend a daily average of nearly 17 minutes each on these sites. That adds up to a lot of page views - almost 4.5 billion per month . And that doesn’t take into account the billion-a-day MySpace page views, which many people argue is basically a very large dating site. All told, at least 15% of U.S. Internet users visit an online dating site each month.

The two largest dating sites are Yahoo Personals and Match.com, respectively, with a combined 9.3 million monthly visitors. Both allow free browsing, but to communicate with other members you must pay a fee. Match.com charges $30/month for the basic plan; Yahoo’s fee is $25/month. Both sites also offer premium plans that attempt to help you find a compatible mate.

An entire batch of next generation dating sites have emerged that are starting to nip at the established players. One, PlentyofFish, launched in 2003 and has over half a million monthly U.S. visitors. Recently, even Google has entered the space through their Google Base product.

One big difference is that these sites are (mostly) free, making revenue from ad sales alone. But many of these sites are also experimenting with new ways to introduce people who may be a good match.

Frankly, such an objective breakdown of the services may be of little value to users looking to just find a date. Numbers of profiles matter - in that case PlentyofFish, a basic but free service, leads the pack. If you are looking for a more structures approach to dating, try one of the sites offering activity based meetings, or matchmaking. Most anticipated favorite is MingleNow - tying socializing to real-world hangouts is a great idea. Most of the sites support gay and lesbian searches as well.