IT’S HARD TO IMPROVE on the computer mouse without making it harder to use. Microsoft’s IntelliMouse ($84.95) adds a great new feature–a rubber wheel between the right and left buttons–that makes scrolling a joy. Rolling the wheel toward you scrolls text down, rolling away scrolls it up. Depressing the wheel itself scrolls text continuously, like movie credits. Right now, few programs support the device (Microsoft Explorer 3.0 does); Office 97 programs will use it. If you’re looking for a desktop accessory that doesn’t require compatibility, try Kensington’s supercomfortable Contour Wrist Pad ($18.95).