Black text on yellow is good for your eyes. Smart people like Micheal Tsai and Wincent Colaiuta even think so. I've been using this set up since the CodeWarrior days (before they went Freescale).

Initially, you won't perceive any immediate or significant change. As you get used to the color scheme, in other editors you will notice the absence of kindness to your eyes. We can thank the physiological characteristics of the eye; earth-bound humans are most sensitive to yellowish-green light. The black text on light-yellow allows for high contrast, eye-friendly display.

If you Xcode or Textmate, consider giving your eyes a rest. Fully saturated yellow (like a smiley face) is not going to help you at all. By now, you are probably asking yourself, "Self? What kind of yellow do I really want to look at for some ridiculous number of hours a day?" Fortuitously, answers are at hand.

In the Mac OS X color picker, there is a sliders-based option in the toolbar (second from the left on the standard Tiger mini-picker). In the pop-up menu select CMYK Sliders and set everything to 0. Push Yellow up to around 20-25% and you are on your way to being rich and famous.

Everything accounted for, color schemes are a very small part of reducing computer related eyestrain. If your eyes are pestering you for some help (itchy, watery, sore, etc.), do some proper research and improve your environment. Happy rods and cones make happy developers.

Disclaimer: Results may vary for organisms orbiting red or blue stars.