Using Emotiv's EPOC brain-reading headset, you can now search Flickr and tag pictures based on how happy, sad, angry, or scared they make you.
The EmoLens app for Emotive's EPOC brainwave-sensing headset is capable of detecting four separate emotions, and uses those emotions to control the speed of a Flickr slideshow while simultaneously adding emotion tags to images. For example, if you look at an image that makes you happy, the headset can tell, and the app will add a "happy" tag and then pause on the image until it ceases to make you happy, whereupon the slideshow will continue. Watch it in action:
EmoLens also lets you use a couple different concentration states combined with blinks and shakes of the head to navigate a specialized Flickr interface, meaning that the entire process is completely hands-free. In fact, it's nearly completely movement-free, period. Score one for lazy computer users like me.