How many of Unity’s keyboard shortcuts do you know? Probably not as many as you’d like!
For Ubuntu 12.04 a ‘shortcut overlay hint‘ will appear on screen when the Super key (Aka ‘Windows key’) is pressed and held. The overlay presents a list of key-combos for accessing and navigating various Unity features.
To maintain the Unity feel the hint cheat-sheet uses the same border and transparent look as Oneiric’s Alt+Tab switcher.
The overlay is the work of the awesome Andrea Azzarone, and fixes this bug.