This is a very cool visual dictionary. Type in a word and it combines wiktionary content with Flickr images. You can set it to pull from Google and Yahoo images, too, but the richest images are from Flickr. Very interesting to see images for the more intangible nouns such as love and hope. This could be a great tool useful for building a vocabulary wiki for a class.
Just a word of caution. I tried the word "anger" and ended up with a topless woman from Flickr. Granted, the photo was done very artistically, but the images are more definitely NOT censored.
One of the best ways to infuse technology into your classroom experience is to have students create their own primary data with a digital camera. Cameras are an easy to use and motivating tool for students. Instead of searching the Internet for a copyright free image to use, have them create their own pictures whenever possible.
In image processing, computer graphics, and photography, high dynamic range imaging (HDRI or just HDR) is a set of techniques that allows a greater dynamic range of luminances between light and dark areas of a scene than normal digital imaging techniques. The intention of HDRI is to accurately represent the wide range of intensity levels found in real scenes ranging from direct sunlight to shadows.