Screen-grab showing the Google Map for Tokyo just full up with all sorts of little icon ads from various businesses, particularly fast-food and convenience store companies.
(Click the "all sizes" icon above the picture in order to expand it and better see all the icons.)
I mentioned this on my blog in a post titled, Google Maps could be chocked full-O-ads.
12/7/2009: I mentioned this map image in an article on Achieving Landmark Icon Status In Google Maps - an examination of what factors Google Maps may be using for deciding which businesses receive landmark icon status in the United States.
3/18/2010: UPDATE! Mike Blumenthal notes how Google Maps has now begun testing similar icon ads in Australia.