A system tray icon sprite sheet.
Feeling creative? Make your own version, save as a PNG, drop it in a config directory and - voilà - your systray looks just like you want it to.
There are two sets of icons on the sprite sheet. The first three columns is the XP style, which is a bit puffy and matches well older Windows styling. The last three columns is a flat version that goes better with native W7 tray icon style.
Each icon comes in 3 sizes - 16x16, 20x20, 24x24. This is needed to accommodate 3 common DPI levels, see
this earlier entry