Shirataki is a great pasta substitute:
http://lowcarbdiets.about.com/od/pr...atakinoodle.htm
Soy crisps for potato chips
For baking, xylitol for sugar, almond and hazelnut flour for flour
(I've made cake, cookies & brownies this way that turned out great)
TVP for rice
Cheese, lettuce or celery for bread (depending on use)
Unsalted nuts, berries & plain yogurt for breakfast cereal