TechCrunch has a comprehensive survey of online dating sites here. The one I found most interesting is Prescription4Love.
“Prescription4Love is a niche site devoted to people facing the stigma of special conditions, such as deafness, HIV, or obesity. It helps members find a better romantic match by allowing them to be open about their conditions with potential partners while maintaining anonymity until users trust each other.”
Conspicuously missing from the article is eHarmony.com.
For India, Matrimonials with various nuances (regional, language, caste, matchmaking – see Engage, profession, psychological profiling, family background) is a very attractive category, since the culture has traditionally been arranged marriage driven.
This segment is a part in the series : Concept Arbitrage