Once upon a time I ran a Valentine-Matching site for Livejournal users. (Actually I did it for about three years in a row, but then got bored.)
The basic idea was simple, you'd visit a magical site and it would present you with the usernames of all your friends. You'd tick a few boxes, and that would nominate those users as your potential valentines.
Then you'd do nothing until February 14th, at which point you'd discover if you matched. A match being made if you chose bob, and bob chose you in return.
(Essentially the site is a big double-blind matching system, albeit with constrained membership, via lj.)
The major technical difficulty in early days was preventing spoofed accounts. I didn't want Evil Alice to be able to visit the site and pretend to be Bob. In the couple of years I did this I came up with a couple of fun schemes to minimize the chances of this occuring - anything from using email validation, to requiring that users taking part updated their profiles to include a magic cookie-string, or posting to a specific community which I could later screen-scrape.
These days the use of openid allows me to prevent spoofing in a trivial manner - and once I realised that I figured why the hell not?!
In short here I am and here we go again:
The motivation? Playing with openID and because I still like to "match people up". I am aware of one marriage that resulted from a match on my system back in 2003. There could be more.
If you're a long-time reader you might remember ctrl-alt-date - how time flies - I just let the domain name(s) expire this week. The timing is a little bit of a coincidence, but not entirely.
The only thing that I'm doing this time is not sending emails on matches, because I just can't. Unless I asked people to volunteer their mail addresses I don't have the data. Still I expect remembering to return for the results won't be a challenge.
Now, lets get viral. But not in an icky fashion ..