ease of use

Use the Toolbar Redesign then you automatically use the New Load Progress.

Use your iPad as an external display.

Use one mouse/keyboard to control several Macs.

Use a Mac computer as a video surveillance camera.

Use QuickTime movies as screen savers.

Use your volume keys to adjust the volume in iTunes, via AirPlay.

Use a single iSight or other webcam with multiple applications.

Use Sony Ericsson phones as input devices.

Use Wii Remote to turn any surface to a whiteboard.

Use a MixMan DM2 USB controller with any MIDI compatible app.