
If you've got an Intel Mac, and you've installed Boot Camp, then you're familiar with the boot loader screen. As seen at right, it appears at startup and lets you select whether to boot your Intel Mac into OS X or Windows.
I accidentally discovered this tip -- I was invoking the boot loader when I realized that my Bluetooth mouse worked. Using the mouse, I could select my partition with a double click. The interesting thing is that if you click the arrow icon seen below the partition, then that partition will be set as your Mac's startup disk. For example, if you select the Windows partition, the Mac will then boot into Windows every time you restart it -- unless you hold down the Option key to bring up the boot loader again.
Update: This hint's assertion about permanently changing the boot disk is incorrect, as noted in the comments.

