Well,. yes, actually I have, but I don't want to talk about it 
Like Teddy said, the Internet is the best and worst thing that has happened to relationships. I've been on-line since the Bitnet relay days (1991), and I've seen and heard it all, found love, lost love, affairs, crimes of passion, etc. It hasn't been pretty. But then, in some cases, shamefully few, it's worked out well, as the gentleman below mentioned.
As for the future, it's up to the people, they need to realize the dynamics of on-line relationships. No site can match a person due to a boxed set of 'compatibilities', that's just not giong to work, you need the face time, the real-life compatibility test. The Internet offers a level of anonimity that can help on the one hand, by offering people a chance to feel each other out so to speak without the initial awkwardness of social situations, but it also tends to obscure some very important facts about people that you really need to know to determine whether or not you're compatible with someone. Technology will change, it'll make things easier to connect people, which is how the internet started, as a way to exchange information between government and educational instititions, the whole 'relationship' thing was a predictable side-effect. If you give people a chance to connect, in whatever way, shape or form, they will find a way to turn it into something that works for them.