A useful addition to the world of Minecraft is the Windowed Fullscreen mode for Minecraft. This is quite beneficial for dual screens and Alt-Tab.

Fullscreen Windowed Mod
Downloads:
Fullscreen Windowed Mod for Minecraft 1.5.2:
Fullscreen Mod for Minecraft 1.5.1:
Installation:
- Download and install Minecraft Forge
- Download Fullscreen Windowed Mod
- Simply extract inside your minecraft.jar and press F12 to set the fullscreen windowed mode.
- Done
- Enjoy!!!