iTunes auto-check box

Command-clicking the "check mark" boxes in iTunes will check all/none automatically.

Jerky Move Tool

In Autodesk's Maya, if the move tool is behaving as though snapping is turned, but it's not, check the tool's preferences (by double clicking on its icon) to see if "discrete move" is turned on. Turning it on will result in the aforementioned jerky movements, turning it off will restore it to normal.