Widget Wonders Meet the web applets that interact with your desktop 24/7/365.

One of the few truisms left in computing: If you want to know what you'll be doing on a Windows PC tomorrow, check out what's happening on a Mac today. And what's happening is widgets--small pieces of HTML, JavaScript or other web code that get downloaded to the Mac's Dashboard, where they can do any number of internet-ish things.

A widget might be used to monitor an eBay auction, a stock ticker or a videocam; it might update the content of your favorite blogs automatically. A widget could be a digital clock, calendar, company wiki, game or virtual aquarium for your virtual fish.

It's unclear whether Apple or former Mac developer Konfabulator invented widgets. But, like so many PC innovations before them, they incubated in Cupertino's creative ooze and were ushered into widespread use by Mac OS X. Thousands are available for download as freeware or shareware from Apple's website to monitor, measure or count everything from disk space to days left 'til The Simpsons movie.

Widgets have also been creeping onto Windows PCs and handhelds in recent months--primarily through web portals like Google and Yahoo! (which acquired Konfabulator) and browsers like Opera and Firefox. Whether called gadgets, kapsules, desklets or widsets, they're a quick way to add content to a Google or Yahoo! home page, domain, blog or MySpace page.

Swapping widgets can help direct traffic among partner sites and complement your other marketing efforts. For example, Janine Popick, CEO of direct marketer VerticalResponse Inc., gives away a simple sign-up widget that helps websites collect subscription information from visitors. In its first week on the web, a quarter of those notified of the widget downloaded it--a far better conversion rate than the 1 percent to 3 percent most mass mailings generate, she notes. The VerticalResponse widget helps drive traffic to Popick's blog and build readership for her newsletter promoting her services. Popick, 39, built a 35-person company with annual sales north of $7 million using complementary marketing methods like these.

Many other widgets are simply diversions--some appeal primarily to aficionados. But in this era of consumer-driven interactivity and buzz marketing, even a fizz experiment (see www.eepybird.com) can help circumscribe communities of like-minded customers.

Gindows Gadgets
Vista will be another major boost for widgets--or gadgets, as Microsoft calls them. More than 500 ga-widgets are available on Microsoft's site, covering pretty much the same ground as Mac widgets. They get housed in Sidebar, an Apple Dashboard-like windowpane on the Vista desktop.

Windows XP doesn't have Sidebar or Microsoft-blessed gadgets. But the above-mentioned third parties will make sure XP users don't go wanting. Widgets are easily ported among platforms--by their publishers, if not by users. And they won't be confined to desktops.

You know that little LCD on your cell phone's lid that updates things like time, date and battery life? Imagine a slightly larger one with navigation keys on your laptop's lid. Vista supports another new hardware/software feature called SideShow that lets you cycle through Sidebar gadgets without fully powering up your notebook.

Because SideShow needs extra hardware like a secondary display and co-processor, these laptops will roll out gradually, vendor by vendor. ASUSTeK Computer and LG Electronics are getting a jump on the competition by using Preface, a turnkey SideShow subsystem from PortalPlayer. PortalPlayer has a relationship with NVIDIA, whose graphics co-processors enable many laptops to stream music, video and other really rich media.

The Small Time
It's an interesting contrast to the five years, thousands of employees and gazillion dollars Microsoft needed to revamp its ginormous operating system and mega-Office Suite. One company owning 80 percent of the software market--that's so 20th century.

Widgets are entrepreneurial: In a few hours, one person codes something you never even dreamed of wanting because it would be too granular for mass market software. Widgets aim even more narrowly than most web-based services.

They're tiny blows against the monopoly and more evidence of the internet's ascendancy.

• Gatesian Gadgets: Download headlines; Twitter your friends; take a poll.
• Google Gadgets: Track travel rewards; catch a bee; meter your mood.
• MacWidgets: Search TV listings; grow virtual herbs on your virtual Chia Pet.
• Nokia WidSets: Play phone games; swap Flickr pix; check the weather in Macedonia.
• Opera Widgets: Widgetize! your own ideas for desktop or cell phone.
• SpringWidgets: Harvest widgets from other platforms.
• Widgetbox: Where's that widget hiding?
• Yahoo! Widgets: Control your iPod; watch Old Faithful blow its top.

Mike Hogan is Entrepreneur's technology editor.