WattOS is one of my favorite lightweight distributions, despite a few minor quibbles about configuration options. Yesterday, the newest version, wattOS R4, was released. Among the changes are a "control panel user interface for simple configuration of your system in a familiar format" and a couple of changes to lighter software defaults, most notably switching from Firefox to Chromium as the default browser.
I also like the new logo wattOS has adopted. It goes better with the default color scheme (assuming the default theme is still green-based) and may not look quite as awkward as part of the menu button.
PlanetWatt - wattOS R4