Planning to go somewhere? London, Birmingham, Exeter airport, Barnstable hospital, Plymouth, railway station, wherever? Just enter details of your trip here and soon you will receive car sharing offers from car drivers planning a similar journey.
The cost? At least 5 times less than a taxi, much less than rail ticket, less than bus - just sharing the cost of fuel.
Its an excellent idea, and appears to be well executed.

(Thanks to Paul Sousek)