Popular Flickr photos and YouTube videos have hundreds of comments, and if you're interested in what the crowd thinks that's a lot to read. OpinionCloud, a Firefox extension, adds a useful cloud to Flickr and YouTube pages giving you a quick way to scan peoples thoughts.
When installed and activated, OpinionCloud will load an extra part to pages full of red and green words of different sizes. The bigger the word, the more common, and the colors denote positive or negative comments.
Whether or not this is extremely useful or not, word clouds are a neat way to skim information so OpinionCoud makes a nice addition to Flickr and YouTube. Unfortunately, this version has broken the YouTube compatibility, which should be returning in the next one. Another problem with it is that it does slow down loading pages if there are lots and lots of comments.
As a way of gauging popular opinion in moments, OpinionCloud is pretty useful, although it would be nice if it was compatible with more websites!