My latest piece in Crosscut.com is on the recent addition of white-on-brown street signs to Seattle's inventory. They are meant to mark our network of Olmsted boulevards, and mark only the third color scheme that I am aware of in Seattle's street sign history (black on white till the 1960s, white on green since then).
If you're an "address nerd" like me and want to see more pictures of Seattle street signs, I also invite you to check out my Flickr set and Morgan Wick's gallery.