I use this collection of icons myself on my both my Netbook and my desktop and totally love them! Pretty much every icon is covered.
Mash Up mixes up icons from many different sources – such as Oxygen, Crystal, Tango and more but also has a few custom icons created by the maintainer. By combining the best icons from the best themes it, quite literally, is one of the best icons themes!
Mashup is a light 7MB and includes icons your system uses. Gnome, Evolution, Epiphany and Rhythmbox will be happy.
There are a few icons I don’t like such as the Firefox Icon, Volume icon and a few other system icons that are a bit too similar to each other. Small complaints that are easily solved by just picking a different icon.
You can grab this very awesome icon set from Gnome-Look by clicking here.