Forgotten my username and password, mail address already in use

[Joost Kraaijeveld]

Hi,

I have forgotten my username (and password). But I somehow have an
account because I can not create a new account as the site says:
"Warning: The email address specified is already in use. Please specify
a different one."

Is it possible to retrieve my username?

--
Groeten,

Joost Kraaijeveld