There's also a back-lit screen that displays both a clock and stopwatch.

FORBES: Magazine Article

It also has 64 MB of memory, a back-lit screen that incorporates a stopwatch and a clock, and an FM tuner for listening to the radio.

FORBES: Rio, Redesigned

In 2003, Nintendo released the completely redesigned Game Boy Advance SP which, most importantly, added a front-lit screen, attempting rectifying the one major problem people had with the original GBA. Recently, Nintendo released yet another GBA varient, the Game Boy Micro, with a small and sleek design aimed in large part at an older, iPod-totting audience.

ENGADGET: A Brief History of Handheld Video Games