This time, he's created the Townland Explorer. It allows researchers to search a Superintendent Registrar District (an area which administered the civil registration of births, marriages and deaths) to reveal a list of all the civil parishes and towns included within the Registrar's District. These towns can then be further interrogated for lists of all the townlands they cover.
The Townland Explorer will be a very helpful and easy route to understanding the areas covered by each district. Its content comes from the General Alphabetical Index to the Townlands and Towns, Parishes & Baronies of Ireland (1861), which was based on the data used for the 1851 Irish census. And it's free. There's also a handy tutorial here.
Great work, Shane!
See below for a screengrab of data returned from a search of towns in the Skibbereen Registrar's District of South West Cork.