Popular GIS Applications
Before consumer GPS devices were so prevalent we used to have to go to a computer and look- up directions, such as with Bing Maps. (Bing Maps is a relatively new service, which grew out of Microsoft Virtual Earth.) Bing Maps has some great features such as oblique imagery (Bird's Eye View), Streaming Video, and Photosynth.
Many websites incorporate data from Bing or other GIS sources to provide a limited mapping experience on their own websites (such as seeing all their physical storefronts).
Traditionally desktop GIS has dominated the GIS mindset. People think of ArcMap, Micro Station, or other enterprise-level GIS applications when they think desktop GIS.
But the most prevalent desktop GIS application is free, and quiet powerful. With over 400 million total downloads (according to Geo Web 2008 keynote speech by Michael Jones) Google Earth is by far the most used GIS application in the world. While many people use Google Earth to look for fun things such as a friend's house, crop circles, and other oddities, Google Earth also allows you to add georeferenced images, view parcel data, and find routes.