Companies much as FTDNA or YSEQ.NET now offer multi-SNP tests to identify sub-branches of M222. These sub-branches can define a geographic origin to your ancestor.
These sub-branches have been identified from member of M222 population taking the Big-Y test (like myself) and sharing the data.
Ninety percent of M222 tests belong to major sub-branch S660 (which I argue is the Connachta). This breaks into a least 11 know sub-groups
A259+ associated with Ui Briuin surnames
Its major sub-branches is A260, which breaks into A883 (and A887 under that), FGC5939 and the little known Z70.
D85 and its sub-branch is associated with some Cenel Conaill surnames of Donegal.
S588 and its sub-branch is associated with some Cenel Eoghain surnames of Derry.
A223 and its sub-branch is associated with some Cenel Conaill and Scottish surnames.
A738 is associated with Irish Midland surnames, including my own Morgan surname whose origin includes variants such as Moran and Moragan.
There are a number of other branches yet fully defined: PF3292, A1206, FGC4133 and others with only one Big-Y testee some far announced.
"We Need You!"
BernardMorgan at hotmail.com
As with all M222 testees I recommend joining M222 mailing list: http://lists.rootsweb.ancestry.com/index/other/DNA/DNA-R1B1C7.html
and the M222 and Ireland DNA projects.