I do love those freckles on the belly. Mo has them, so I may be biased?
I'm not very good at naming. I'd suggest something to go along with the personality, or looks, as Rachael suggested. I know a chi named Speck..he has a freckle in the midddle of his nose like Mo. The name Speck also goes well with their size
Other options, Dotty (better for girl), or the old standby Spot?