Moodstream by Getty Images is a website that either conforms to, or helps shape, you mood. Its hard to tell exactly what it is or what it does.
When you first get to the web site it loads a bunch of images to cycle through and starts playing music. you can tweak the type of images you see manually or load one of the presets. Then, stare and listen. You can alter the settings at any time. This qualifies as one of those sites that you just have to visit to truly understand.