You can find lots of fun, useful, eye-catching, and (best of all) free desktop gadgets, themes, and backgrounds (wallpapers) for Windows 7 in the Personalization Gallery. But that's just a selection of the most highly-rated and top-downloaded gadgets—you can download thousands more desktop and SideShow gadgets in the Windows Live Gallery—including stock market tickers, RSS readers, and weather and temperature gadgets.
You'll also find currency calculators, notepads, sticky notes, calendars, clocks, timers, countdown and alarm gadgets, and useful system tools such as CPU meters and battery monitors.
Not to mention reference tools (like dictionary gadgets) and gadgets that integrate with popular programs or websites, like Outlook, Facebook, iTunes, Pandora, and Gmail. To find these and many more, visit the Windows Live Gallery.