Tipatag for Android is a scanner application that scans "Tipatags". A "Tipatag" is a meaningful visual tag, readable with a smartphone's camera. These tags can be created for free in http://www.tipatag.com. You can create tags using pictures or photographs of your choice and associate them with particular actions such as showing a video, twitting something or posting an image or text on the reader's facebook wall. Reading the tag will trigger that action. In order to read a tag just launch the Tipatag mobile application. The application opens instantly in scanner mode.
Want to try it? Just scan some tags in http://tipatag.com/entry/gallery and see what happens!