I'm adding this to big-up the Telephone Preference Service!
Some of you may already know about it, but I'm betting there are still quite alot of people who have never heard of it.
Basically it is a service which adds your number to a list of numbers that are not to be rung by salesmen. As far as I can tell it was set-up with things like Doctor's surgeries in mind - where receiving sales calls could create problems for people by clogging up the line.
Registering is free - the website says it may take up to 28 days for your number to be added to the list.
After that tell any salesmen who ring you that you are TPS registered, they usually apologise and say they will take your number off their database.
Gotta love them!