There are particular boundaries used by NISRA, mainly for census purposes:
Super Output Areas (SOA), nest within Wards which are already on ODNI
Small Areas (SA), nest within SOAs
* Output Areas (OA) pre-2011 census data, nest within SOAs
While NISRA publish these boundaries as Shapefiles on their site (e.g. http://www.nisra.gov.uk/geography/SmallAreas.htm), under the Open Government Licence, it would be useful to have these hosted here, especially as more statistical geography data, to which these boundaries relate, start to be published on ODNI.
Providing alternative open formats (geojson, kml) is also important.