Google keeps expanding the features of its Google Maps API, yet there's no shortage of things developers wish Google added. We know this because there is a public repository of issues. While some may be bugs, most are enhancements, desired additions to the web's most popular API.
Five years ago Paul Rademacher reverse engineered Google Maps to put Craigslist homes and rentals on a map on his site. The site essentially pre-launched the map mashup category, because there was no Google Maps API at the time. Now it is the prototypical example and still used by many to find their new homes. And, of course, Google Maps is now by far the most popular API to use.