Although a British Crown Dependency, the Isle of Man has its own coins, banknotes as well as postage stamps. As Head of State, an effigy of Her Majesty Queen Elizabeth II, Lord of Mann appears on all Isle of Man Coins.
Although these coins are not legal on the UK mainland as they are the same size they might sometimes find thier way into peoples pockets and be lost for detectorists to find.
Here is some good information about the Manx coinage
Numista has images and details of most of the coins
The Isle of Man has produced a significant number of stunning commemorative coins, these are some highlights.