I have recently launched a new series of caches and called it the Geosquare series.
The Ordnance Survey (OS) National Grid provides a unique reference system, which can be seen on all Ordnance Survey maps of Great Britain. Great Britain is covered by 100 kilometre grid squares, each grid square is identified by two letters. On Ordnance Survey maps these squares are further divided into smaller 1 km squares by grid lines representing 1 kilometre spacing, each numbered from 0 to 99 from the south-west corner, in an easterly (left to right) and northerly (upwards) direction.
In the Geosquare series the cache is named after the 1 km square in which it is placed. Others are welcome to add to the series, using the logo, sidebar and description.
The first cache in the series was Geosquare SP2382 - Middle England and is as the name suggests in the middle of England - in Meriden. As of November 2012 there are six caches in the Geosquare series.
I should emphasise that the idea is not to saturate a 100 km square with Geosquare caches. The quality of caches needs to be maintained, and above all the safety of the geocache needs to be born in mind.
I've got a lot of ideas of how to develop the series, in particular with challenges e.g. finding five Geosquare cahes in a row:
How about Geosquare Battleship, where the idea would be to find adjoining Geosquare caches in a 100 km square matching the Battleship game rules.
If the idea takes off then the ultimate Geosquare Challenge would be to find a Geosquare cache in each of the 100 Km squares:-
