GeoImpress let's you search for Flickr photographs and Tweets from any location in the world. This is a very crowded market to enter. There have been more Google Map mashups that use Flickr than any other website, with Twitter mashups catching up fast.
However GeoImpress does indeed impress, thanks to its wonderful design. Flickr photographs are shown below the map in an animated slide panel that can be lowered or raised as you need to use the map. Clicking on a photo thumbnail will open that picture in a lightbox.
Another really nice feature is the precision slidebar that lets the user define how close to the set location they wish to search. So, for example, if you set the location to Times Square you can get the map to display photos and Tweets from Times Square, or widen the search to get results from the outlying district or widen out further to include the whole city or state.
Yep, I'm impressed.