I believe you can be attracted to someone at first sight, and end up in love, and in a relationship, but I don't believe you can truly LOVE at first sight. To me Love goes so far past the surface that it would be impossible before you know who the other person is.
I didn't belived it; until I met my boyfriend. I felt a big "BANG!" in my heart as soon as I saw him. That's when I understood what a "coup de foudre" means. We spoke together the whole night. It was in a party at my home (he had been invited by a friend), there was lot of people, but it could easily have been only the two of us.
At the end of the night, he gave me is email, but I was so excited that... I lost it. It's like he had never existed, none of my friend could help me find it back, not even the one who brought it to my house. Took me more than a year to see him again!
But it was all worth it; I'm happy to say that we've been together for more than two years now
Oh hell, there is. I've seen some examples of people who were actually able to have a strong crush on a person they just got to know. Of course, *mutual* love at first sight is even more rare and complicated... Maintaining a relationship is more difficult than adoring someone you can't reach, and only time can prove it to be an actual love.