Mac only: Radiant Player (formerly known as Google Music for Mac) has gone through quite a few updates since we featured it two months ago. Now it has some handy swipe gestures, a mini player, extra themes and Last.fm integration.
If you missed it the first time around, Radiant Player is a standalone music app for OS X that connects to your Google Play Music library, perfect for playing your cloud tunes. It supports media keys, all of Play Music's radio features and desktop notifications. It now also features swipe gestures to navigate backwards and forwards (provided you have the right settings enabled on your Mac), a mini-player in the menu bar, Last.fm scrobbling and a number of darker themes.
If you like the idea of Google Play Music but want a more desktop-friendly app, this one's only getting better. Hit the link to download the latest version.
Radiant Player [GitHub]