How about:

PUPLV

My mind isn't working to well right now and that's all I can think of.

Here in Michigan we have 7 letters. I've also been thinking about going to a vanity plate. Here's what I've thought up so far (didn't think of it right now, I've written them down)

Moosmom
Catluvr
CatResQ
Petalk1
Catmom5
LuvCats