TouchCounters are computational tags that track the usage of physical objects. TouchCounters sense activity through magnetic, acceleration, and infrared sensors, and indicate their status on bright LED displays. Through magnetic snap connectors, TouchCounters can be networked to a web server that generates use histograms for each object. Just as "hit counters" indicate frequency of use for web pages, TouchCounters indicate usage frequency for physical objects.
(Source: http://tangible.media.mit.edu/projects/touchcounters/)