Here's a downloadable PDF of Taco Bell's nutrition facts.
TacoBell.com
Order just about any menu item as "Fresco" and that will cut the calories significantly. When you say "Fresco Style," they don't put cheese or sauce on your menu item, but they replace it with Pico de Gallo. If you're unfamiliar with Pico de Gallo, it's tomoatoes, onions, peppers, and cilantro. It packs a lot fo flavor and very few additional calories.
They were nice enough to spell it out for us on their website...
http://s28.photobucket.com/albums/c2...t=tacobell.jpg
If you need a side dish,their Pintos (no cheese) and their Rice are both under 200 calories.
Their hot sauces are basically water, vinegar, peppers, salt, and some sugar. They're not too bad.