In Irish, sometimes a pet form of Cait (with fada over 'a') is used, 'Caitlin' (with fada over 'a' and second 'i'), meaning 'little Cait' (with fada over 'a'). Some Irish people spell Kathleen this way.
I have a dear friend named Caitlyn who goes by Cait. I think her name is very pretty and suits her well. She is as individual as the spelling. I've always loved the Kate family of names. :)
Famous bearer - Cait O'Riordan, formerly of the Pogues. She was married to Elvis Costello until 2002.
PS. I like this version of the 'Kate' family most. My middle name is Caitlin, though, so maybe I'm biased. Would totally use it if I ever needed to change my name.