Custom Property with multi-select drop-down

Here is yet another request for a multi-select drop-down custom property.  From previous threads I've read, this is apparently quite difficult to implement.  Well SolarWinds, are you up for the challenge?

My use-case for a one-to-many CP is a property called Business_Services.  This field would have a drop-down list of all the services impacted by the node in question if it went offline.  Based on the selected services you could send targeted emails to service owners.

I'm sure there would be a plethora of other uses.  I'd like to hear everyone’s feedback.