Bitchin' Widget
If you don't know what Widgets on a Mac are, well, they're what made Microsoft to put "Gadgets" in Windows Vista. The Mac has a "Dashboard" which can be easily invoked (a leading icon in the Dock, a click of the scroll button on my wireless mouse) and has a startling variety of resident programs with which you can clutter up your computing experience. I have, let's get graceless and enumerative here, a 600 mile doppler weather map, a calculator, a stock watcher, a dictionary/thesaurus, a Skype widget (which I don't really use), an analog clock, a calendar, a package tracker (for UPS, FedEx and DHL), another weather widget with a 5-day forecast and finally, the new one: "Mighty Monitor." It's a "fuel gauge" for the battery life on my wireless mouse and keyboard. Very handy. The same info was avaialbe in my system preference but I would have to launch the preferences, choose "mouse and keyboard" and then possibly click on one of the options therein. Now, 'click' oh, good plenty of juice left. Brilliant!
Here's the page, if you want to cast an eye on it. And the hat tip must go to the invaluable The Unofficial Apple Weblog.