Where else can I post adverts to do with Cambridge?

cam.* isn't your only option. Other places you could try are:

• Tim Ward runs the Cambridge Accommodation Notice Board which take adverts.
• Cambridge Freecycle and Fridge Mountain are good places to put adverts for things you want to give away (but only for free, you can't lend, rent, or swap either.)
• Cambridge University runs a set of newsgroups, including ones for things for sale, things to give away, computers for sale, and things wanted. See the list of Announcement and Advertisement Newsgroups for full details. Only those within the university can post to these directly, however other people can post to them by crossposting to another (preferably relevant) newsgroup at the same time.