These wikipedia links will be good starting points but not necessarily good sources. Use them with some salt. Memorize the saints names maybe and use them like cursewords.
Hey, Conchobro, you should probably know these two guys.
This Cellach guy, very important reformer. Before him, the leader of the Irish Christians was a layman. http://en.wikipedia.org/wiki/Saint_Cellach
The background on this one basically says that by the 11th century some Irishs had reverted to paganism, but this guy helped convert them back. http://en.wikipedia.org/wiki/Malachy_O%27More
These guys might make better stories, since they’re martyrs.
- http://en.wikipedia.org/wiki/Coloman_of_Stockerau (actually maybe irish, so him first)
- http://en.wikipedia.org/wiki/Hallvard_Vebj%C3%B8rnsson (norse)
Note that in those two links, the pages are all named the same, so you can go up and down centuries by changing the numbers.