I just recently discovered this timesaver of a feature in AutoCAD 2006. If you've ever wished you could just temporarily switch a setting for use in a command, you'll like the new Temporary Overrides.
Now you can override a particular setting with a specific combination of keys. For example, holding the Shift key down toggles Orthomode on and off (very handy!).
Shift+A – toggle object snap mode
Shift+E – turns on endpoint osnap only
Shift+M – turns on midpoint osnap only
Shift+C – turns on center osnap only
Shift+Q – toggles Object Tracking
Shift+X – toggles Polar Mode
These are just a few examples, there are plenty more, and you can easily change them or add more in the new CUI (see Monday's blog).