A glow, only if they really deserve it though, if the ex staff member has contributed more than enough to this site then I reckon that they should receive a glow to their name, to show everyone that, that member has done more than enough for this site.
This is just a suggestion, I think it'd be nice to have, as most ex staff aren't as active as they used to be, if they see themselves as getting more recognized for their contribution then maybe they'll see reasons to stay, I also know that some members' are ex - staff for certain reasons. (I.E Personal Problems).
Altogether, I think it's a nice feature to have. ^_^