Here's the top baby names in Ireland for 2005, as reported by the Central Bureau of Statistics.
I put the Irish names in green (of course!).
In the boys' list, there are 8 Irish names in the top 25, and I suspect that Ryan is in there more because it's a "modern" name, rather than having a long, Irish heritage (it was used primarily as a last name only in previous centuries).
The Girls have 6 Irish names in their top 25, though I'm thinking that Molly may be used more for it's old-fashioned charm than it's Irishness (along the lines of Sophie, Lucy, Katie, Emily etc.)
Why people use names has always fascinated me, but that's a whole other ballgame!
If you want some historical Irish names for your baby (or your D&D character), check out Fantasy Ireland's Top Baby Names. I always find it fascinating what names people gravitate towards and why-- this site gives information as to why each name is cool in their eyes.