Are you super paranoid? Do you need to have your computer locked from use whenever you're away? Do you tremble in fear worrying about ppl playing around on your precious Mac? Are you too lazy to type in your account password? Is your self image that of a super spy? Here's a new option. Take one rohos lock program and one iPhone / iPod Touch to make a Mac USB computer security key.
First grab rohos and install.
Run rohos and hit "Choose USB key device"
Select your iPhone and "Choose USB"
Type your password
Turn the Key on
Great! Your iPhone / iPod Touch is now a usb security Key. To lock your computer unplug your iPhone / iPod Touch. To unlock plug it in. Of course you can also make flash drives etc into a security key as well but what's the fun in that?
The downsides. The software is a free trial you have to buy it or abandon it after 15 days. The rohos software on windows doesn't allow selection of the iPhone / iPod Touch as a USB device. You will get ridiculed by normal people if you use this in public.