I have no personal experience here but what the heck.... I don't think there's anything weird about someone meeting their partner through an mainstream dating/matching website. If anything it's more likely to help you find someone with the a good ratio of similar:dissimilar interests. I sometimes wish my girlfriend and I had more interests in common, however I would not want a girlfiend who could sit discuss the relative merits of PHP over ASP for a database-driven website or the best way syncronise remote video feeds.

Chat rooms and IRC are another matter, my flatmate from Uni met his (now) wife on IRC and they couldn't be happier, she gave up a promising job and moved from SoCal to rainy miserable Salford to live with him in a miserable student house so she must've been serious. However my ex-boss left his wife and children for someone he met in a chat room, the relationship lasted about six months because she wouldn't stop shagging other men, I never met her but she sounded like decidedly weird, the exact opposite of his ex-wife.

I suppose it's safe to say YMMV, but certainly there shouldn't be any stigma attached to saying you met online.