We have a 'no brass' rule in this house, so I have no brass switch plates on hand. If I did, however, I'd be steampunking them up using The Steampunk Workshop's tutorial. The transformation from what they looked like before to what they look like now is rather shocking.
TSW used some salvaged brass components and ammonia to get that rich patina. Pictured below are more creations using the same batch of switch plates, all of which were made using the same techniques. For the entire tutorial, visit The Steampunk Workshop.