Yes - met DH on a dating site, been together 6 years, married 3.
We took things REALLY slowly, talked a lot, and talked a lot about the fact that we weren't in the same city made things easier AND harder.
It was easier because we got to have all the heady rush of longing for each other, all the flirty emails and we were sort of forced to take it quite slowly, too, which was good for me cos I was wary after a nasty breakup, so I found it nice that I had a new boyfriend but he wasn't all over my life just yet ... and in the long term, it was easier because we had to learn to really talk and really listen to each other (hours on skype!), which I think set us up well for a good relationship.
It was harder because in some ways it was a false... well not quite false, but 'different' intimacy, talking and talking, it's not the same as realising that it's annoying when he leaves his socks there, or whatever. And it meant when we DID see each other we had whole weekends free for each other and wore our best pants etc, which is NOT what living together is like. I suspect we stayed in the 'honeymoon' phase for longer because we didn't live in the same city.
And long-distance is bloody hard work whenever or however it starts, and good fodder for unnecessary drama. Plus you have fights but no makeup sex! that's not fun.
In the long run, it worked well for us, and he's lovely and everything I could want, after 2 years apart at the start and then all these years together... I definitely think I got to know him REALLY well before getting close to thinking about moving in together, which helped.
I think there's a lot less stigma about meeting people online now, though my Mum hasn't got over it yet 