Similarly, PerfectMatch.com puts users on different "message tracks" based on their profile and what they're doing on the site at any given time. "Everything you do or don't do triggers a response," says Dahl. "We take the information and do a comparative analysis on the fly to serve up the best possible offers to you based on your profile."
Users who aren't "taking full advantage of the site" -- who haven't posted a photo, for example, or have failed to review all their matches -- are targeted by the system. "You will get an e-mail message custom to your situation, encouraging you to perform the action needed," Dahl says.
eHarmony, which has the most comprehensive user profiles, may be the most sophisticated in the ways in which it leverages that information. It pulls information -- more than a terabyte of data each day -- from its Oracle database into high-performance Netezza data warehouse appliances that slice and dice users into behavioral and demographic "buckets."
"We use [Netezza] to do a lot of offline calculations to try to understand patterns and business intelligence about user behavior," explains Essas. Some of that feeds back into the matching process, but it also helps eHarmony persuade users to subscribe to its service. "Because we know more about them, we can target them much better," says Essas. Messaging is tailored to each user's behavior on the site -- and their personality type.
Step 3: Make a high-quality connection
Once users have paid for a subscription, online dating sites offer different tech-driven options for contacting and getting to know prospective dates, everything from chat rooms to instant messaging, e-mail and even video chat.
eHarmony controls the process by moving users through a series of proscribed communication steps on its Web site. The idea is to make users of the site comfortable with each other, but sometimes the technology just gets in the way, or backfires, users say.
Mary, a 45-year-old executive for a large IT consultancy, says the process of moving from eHarmony's prewritten questions and responses to online chat to e-mail to telephone can be tedious when what you really want is to meet someone. "You continuously go through this job interview." Then, after all that, people will suddenly cut off communications. "What happened?" she asks.
Video chat is perhaps the most controversial communication method offered, if only because video sessions often take a "sexual tilt," especially with men, and that drives away the women, says Mark Brooks, editor of Online Personals Watch, a newsletter that covers online dating and social networking sites. Mary explains the situation more plainly: "You go look at their webcam, and they're naked."
Some sites try to police that. True.com, which refers to video chat as "virtual dating," has staffers who constantly watch banks of security monitors that alternate between the 300 to 700 video chat sessions occurring at any one time. Participants who are breaking the rules may be kicked offline for an hour -- or permanently -- or staff may "whisper" a message to them to knock off the deviant behavior. Flashing your breasts, showing a weapon or showing your kids will get you a whisper, while showing "below the belt" body parts or verbal abuse will get you kicked off for an hour. "Porn site girls," underage users and scammers get the boot.
Perhaps the most innovative communication method is virtual dates in a 3-D world. One company, OmniDate, offers an avatar-based virtual dating system that acts as a kind of front end to existing online dating sites and is developing a new version for rollout later this spring that will use photo-realistic avatars. (See Online dating: Avatars tackle the first date for you for a glimpse of just how foxy one reporter can look online.)
So far, few sites have adopted the technology. Frind at Plenty of Fish decided to pass. "At the end of the day, it creates a false sense of reality for people. The point is to meet someone as quickly as possible," he says.
Step 4: Weeding out cheats, scammers and married guys
Mary, who says she has used most of the major services out there, worries about stalkers and fraudsters when visiting online dating sites -- and for good reason.
Stories of negative user experiences associated with online dating sites range from the woman duped into sending $4,500 in emergency funds to a man she thought was stranded in Nigeria, to pedophiles who scan the online dating sites looking for lonely women with kids to the New York woman who was the victim of a romance scam that cost her $100,000. The Internet Crime Complaint Center's 2007 Internet Crime Report found Internet fraud had risen and that online dating fraud was one of the most commonly reported complaints.
Keeping out the riffraff is a big headache for Plenty of Fish. "Ten percent of sign-ups a day are people trying to scam someone -- or rude, obnoxious people, or spammers," Frind says, adding that he removes about 2,000 suspicious users from the system daily. The issue is such a large problem that Frind has spent more time writing programs to deal with undesirables than he did creating all of the other elements of the service.
Online dating sites use a variety of approaches to detect suspicious accounts. "These are not the sharpest guys out there. They use the same techniques over and over," says PerfectMatch.com's Dahl. He looks for scammers who set up an account and blast e-mail messages to thousands of people, as well as for certain keywords and phrases that might indicate trouble.