A number of people wrote to whack on me for claiming the Tab key was related to the metal tabs on a mechanical typewriter, saying instead that it is short for "tabulator," a device for making tables. In that sense the key name still makes sense on the computer keyboard, although I wonder if people would have thought that before Word came up with its table feature. On systems with monospaced fonts (and even on Macs with proportional fonts), many people still use the space bar to make tables.
Option-Click AirPort Menu for Network Details
If you hold down the Option key while clicking the AirPort menu in Mac OS X 10.5 Leopard, you'll see not just the names of nearby Wi-Fi networks, but additional details about the selected network. Details include the MAC address of the network, the channel used by the base station, the signal strength (a negative number; the closer to zero it is, the stronger the signal), and the transmit rate in megabits per second showing actual network throughput. If you hover the cursor over the name of a network to which you're not connected, a little yellow pop-up shows the signal strength and type of encryption.