Disable page curl animation in Lion's iCal
For some reason, holding Option down with the keyboard shortcuts doesn't work (iCal just beeps at you), but you can change the keyboard shortcuts in System Preferences to include the Option key, then it'll work. 

For example, I changed the shortcut for "Next" from Cmd-Right Arrow to Cmd-Option-Right Arrow and changed "Previous" to Cmd-Option-Left Arrow. Now the keyboard shortcuts will navigate without the annoying page flip animation.

To do this, go to System Preferences, Keyboard, Keyboard Shortcuts, Application Shortcuts, then hit the "+" icon, and enter the following details - Application: iCal, Menu Title: "Next", Keyboard Shortcut: Cmd-Option-Right Arrow. Then hit "+" again and enter Application: iCal, Menu Title: "Previous", Keyboard Shortcut: Cmd-Option-Left Arrow.