Google Earth is now featuring small text-based ads within the Google Earth interface. This is another excellent example of contextual advertising, or showing ads that are directly relevant to what a potential customer is doing at a given moment.
For example I zoomed into Salt Lake City, UT and clicked the "Grocery Stores" layer on the left side of the Google Earth screen. I then clicked on the "Safeway Food & Drug" icon on the map, which popped up information about the store as well as an ad for $5 off online shopping and delivery from Safeway.
View the Google Earth home page
Read more about Google's advertising in Google Earth
P.S. I clicked the Safeway ad (I'm a fan of Albertson's online grocery ordering and delivery service) and discovered that Safeway doesn't actual deliver in Utah so although Google's idea is great, they obviously have a little bit of work to do before this is perfect!