Yeah, it's http://helpdesk.oneorzero.com/ and that is also free.

ClientExec has a nice built in HelpDesk, although not a lot of people like the one built into ModernBill - they say it isn't too good.


Personally, I think it's best to have an open one where there is no need to actually login, the very reason why I'd recommend eSupport from Kayako.
(lol - even though I don't use it yet! )