Which cam.* group should I use?

cam.announce announcements of events etc. The usual etiquette is that if posting there one should set Followup-To: cam.misc, and one shouldn't post follow ups, other than into cam.misc. Here is information on setting Followup-To for various news clients.

cam.transport for posting about transport related matters, including the ever popular bikes versus cars thread. The usual etiquette is not to post transport threads anywhere else in cam.*.

cam.test to check you can make postings to cam.*

cam.sug for postings related to the Cambridge Sun Users Group

cam.misc for everything else