Yes you can do that with "property Tab Builder" in Solidworks
Start > All Programs > solidworks 2015 > Solidworks Tools > Property Tab Builder 2015
Thanks and Regards
E G S Computers India Pvt. Ltd.
Adding to that list is not possible. Why not use the property tab builder? It's still got some areas for improvement but way more useful if you want to have text look-ups.
Another solution is a PDM system that goes in and sets the variable on check-in or check-out because then you can't lie about who did it.