Nuvola

Nuvola is a free software icon set under the GNU LGPL 2.1 license, created by David Vignoni. Originally created for desktop environments like KDE and GNOME, it is also available in packages for Windows and Mac. The final version, 1.0, contains almost 600 icons. The default set is in the PNG graphics format; an SVG version is also available.
The application icons, in particular, colourfully represent a wide variety of commonplace and easily recognised objects.
Uses.
Besides KDE and GNOME, "Nuvola" is used by the Pidgin instant messaging client, the Amarok media player and the KeePass password manager.
Nuvola is the default icon set on the OpenLab GNU/Linux distribution.
It is also used for many purposes on Wikimedia Foundation projects.