Awoken Icon theme is very famous for Linux desktop, it is most rated & most wanted icons I have ever seen. There isofficial PPA for this icon theme but there are no packages for trusty, so these icons are now available in NoobsLab PPA for all current Ubuntu versions/derivatives, and tarball can be downloaded from its official page.
KDE version of this icon theme kAwoken is also available and added to NoobsLab PPA for all current Ubuntu versions/derivatives. kAwOken icon set is minimal redefined available in three different flavors with two color modes. This icon theme also allow you to customize using its command line feature, this icon theme give you choice to choose icons for your light/dark theme.
Changelog for 2.5 Version:
-Added a full-featured colored version! More than 500 icons were re-drawed in colored mode.
-Changed licensing: from cc-by-nc-sa to cc-by-sa! Now the iconset is completely free.
-Iconset updated to Ubuntu 13.04 Raring Ringtail!
-Added ppa for Ubuntu 12.10 Quantal Quetzal and Ubuntu 13.04 Raring Ringtail
-Solved a bug in coloration script
-Secure icons are now available in networkmanager
-New ubuntuone icons, as well as new emoticons for chat
-Added more than 50 xfce4 icons
-Added icons for gnome 3.8 applications: gnome-games, gnome-documents, gnometris, quadrapassel, gnome-boxes, gnome-disks, and more
-Added or redrawed more than 400 icons
-Added more than 200 symbolic icons