Panoramio is an excellent site combining Google Earth with photo gallery. Currently it contains more than 1 million geolocated photos from all corners of the globe. It could be an excellent tool for travel destination research or just for fun. Panoramio photos also available as a separate layer in Google Earth desktop application.

The biggest limitation so far is an absence of digital cameras with GPS integration, so you need to add coordinates for each photo manually by selecting position with interface provided by Google Earth image.

Flickr also provides a similar service, but their UI is not that good as Panoramio’s.

Here are some of my photos added to this site.