iTunesVolume for Mac

From zumuya:

iTunesVolume is an iTunes controller for mouse that floats on your desktop.

This is NOT a software for volume adjustment.
From Slider you not only control the volume in iTunes, but can also launch iTunes, start and stop songs.
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Drag Slider Knob: Play, pause, volume adjustment.
Control-click Slider: Show the context menu.
(...or hold button press on Slider)
Command-drag Slider: Move Slider Position.
Double click Slider: Open / close iTunes Window.
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Some windows will appear when cursor touches Slider.
When you want to click them, touch Slider and move cursor to the window pressing control key.
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You can open the preferences window or quit this application by using the context menu of Slider.
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You can use even CoverSutra skin files. Copy the .coversutraSkin file into:
~/Library/Application Support/iTunesVolume/Artwork Appearances
You will be able to see and use it on the Artwork preferences.