Fastest possible way to registrate

[symptome]

I got "ajax reg" and it's great!
But ...
I want a registration system, where someone just has to enter his desired name and the email address twice.

Then, he gets an email where he's asked to continue the registration process like clicking on the link to verifiy the email address and enter some further information like male/female ....

With that registration system I want a higher registration rate.
People won't leave the process before entering their email address and so I got a bigger chance of more finished registrations.

Do you know something like that?

I saw it at http://forum.chip.de/

Besides: the forum above runs vbseo. At the time I'm writing, there are 21'000 Users online. They got a total of 432'000 Users and more than 6 million threads. Definitely a big board.

Thanks!
Marcel