0800 654 321
This phone number will, when dialled from any phone in the country, connect you to your nearest taxi firm.
This means that wherever you are - even if you yourelf have no idea where you are - you can get home again.
Especially useful when drunk/stoned, provided you can retrieve the phrase Freephone 6-5-4-3-2-1 from your drink/drug addled memory.
My reson for noding this is that no-one seems to know about it and I'm forever answering people who shout out "Does anyone know a cab number" and telling them to phone this number.
I should be on commission or something.
n.b. I have never known the number to work from a mobile phone, either because the system cannot work out where you are, or because there is no agreement in place with the service providers.