[cobalt-users] RaQ3. User checking availability of username?

["House of Jupiter" <montyharris@xxxxxxxxxxxxxxxxxxxx>]

I am selling email addresses, and need something where potential users can
check to see if their username (or alias) is already gone.  They are all
name-based, such as DaveDaniels@xxxxxxxxxxxx, so to begin with the chances
of a clash are small, but eventually I can see I'm going to have problems.
Also, it would be quite nice if they could automatically add themselves, but
only after they have visited a payment page.  Of course, they only should be
able to add one user.  At the moment I am doing this manually, but I can see
as my business becomes more popular I am going to be manually doing
something for a few hours each day which I would imagine could be done
fairly easily by some kind of script.