[marcinignac.com] by Polish artistic programmer / programming artist represents his computer usage from the last 2.5 years.

Each horizontal line represents a single day, while each block stands for a specific use of the computer, such as the color of the most foreground app running at a given moment, a mouse click (red poster), or a keyboard hit (yellow poster). Accordingly, black areas are those periods when the computer is turned off.

See also How Stephen Wolfram Spent the Last 22 Years (behind the Computer).