Shirataki noodles are quite the rage, although I've never actually tried them. I understand that they smell fishy when you first open the package, but that goes away. They claim to be made of naturally water soluble fiber with no fat, sugar, or starch. Supposedly some varieties have zero net carbs and zero calories. They have been recommended for Italian style and Asian style applications. I need to place an Amazon order anyway, so I'm going to give them a try.
Look around at the reviews, that will give you some kind of idea what they are (besides expensive).
EDIT: Now that I've tried them, I can say that I kind of like them in Asian style applications (especially soup). I can't even imagine them with a marinara type sauce, I think they'd be awful. They'd probably be fine with any kind of seafood. The packages are smaller than I realized, so they are even more expensive than I thought. For me, they are pretty close to price prohibitive.