the sixth amendment is a beautiful thing.
the only time I have heard of someone being tried without knowing the identity of their accuser... well two...
first was an undercover drug cop... who eventually had to take off his mask and show his face to the accused but while shielded from view of the gallery.
second is in cases involving "national security". there is an immigration case involving some middle easterners in los angeles that comes to mind. they are being held by the INS... but the US Atty refuses to give any information citing national security.... the other lucky winners are now enjoying the weather in cuba right now.