WSJ - Jan 29 - Laura Brashier is a survivor of cervical cancer. Her treatment left her unable to have sex so she set up a dating site for people like her. Since its creation in 2011, 2Date4Love has enrolled thousands of members. Dating sites now offer hundreds of potential mates at a keystroke. In "Love in the Time of Algoriths" journalist Dan Slater has dug in manfully to explain how technology is transforming how we meet and fall in love. In the late 1970s, Jeffrey Ullman founded Great Expectations, which invited people to record videos of themselves for perusal by potential dates. When Mr. Ullman appeared on the Montel Williams talk show and was asked if he was preying on lonely people, he shot back: "Yes. Just like restaurants prey on the hungry and doctors prey on the sick." There has been an explosion of niche sites, which Mr. Slater covers in salacious depth. There are dating websites for Goths, pet lovers, military widows and even adults who like to dress up in diapers. Mr. Slater also made a trip to Colombia with a group of American men, members of AmoLatina. For $1,595 a head, the men travel to Medellín, attend two "socials" where there are 20 women for each man, and have the services of concierges and translators to help them with their dates.