First off,
Tom,
Nick, and
Will are great, while
Jim,
Mandy, and
Emmie are horrible. *shrug* I think nicknames need to depend on the name -
James is short enough; while
Catriona actually needs that "Cate"/"Cat"/"Riona".
In my opinion, if you want to call your kid
Tom,
Nick,
Will,
Jim, or
Mandy - name them that.