These may look more like "Graphics" examples (and they are too in a way), but these are in fact automated, customizable output from a PHP application. These "signature" graphics display live statistics data about the player, including whether they are currently playing the game and on what server. Because of that they are extremely popular for forum posters (because these can be used in ANY forum, not just ours), who can display their stats, and allow their fellow forum readers to see when they are online.
The graphic has 3 parameters in the URL: the player ID, the name of the graphic file they want as the background, and an optional font.
For example, http://bf1942.gametrack.org/sig_990301_
omaha7.png gives us:
We can change the background, and add an optional font parameter for the name,
http://bf1942.gametrack.org/sig_990301_midway4_stencil.png:
Here's the mini version, for forums that have more strict restrictions on
signature sizes. http://bf1942.gametrack.org/sigmini_990301_omaha12_stencil.png:
The PHP code uses a multi-layered caching system to dramatically reduce load instead of re-generating the graphic every time the file is requested.