Since we were discussing Celtic names last night, I decided to look up how these crazy names are spelled/pronounced (Someone had seen a name written as Aoife but didn't know how to pronounce it).
Sian, Darragh, Oisin (boy names) are the Celtic spellings of Sean, Dara and Osheen
Aoife, Niamh, Caoimhe (girl names) are the Celtic spellings of Eva, Neeve, and Kiva
But it does remind me that one of the characters in a book I read a while back (Labyrinth, which I didn't like) was Shelagh. Now I'm pretty sure it's just pronounced like Sheila (see: Darragh), but back then I just called the character Sch-lay-gey.