i understand you.i have sometimes feeling like that too.i was chewing soother until i was 5 and my parents thought it was lil weird lol.i would probably chew it until i was 10 if they didn't take it away from me.

you can chew gum or those bear-shaped candies that you need to chew for a long time before swallow.

Hi,
How about sugar-free Jello or those sugar-free popsicles? I would steer clear of chewing ice -- you'll end up with a cracked tooth and need an expensive crown. Not worth it!
~zeez
ps When I'm at home and I need to be chewing/grazing/feeding.... I'll get sunflower seeds in the shell and eat them one at a time. Takes a bit to get through the shell and get to the seed. They're kinda messy at work. Usually I know it's time to quit when my lip gets sore! Oh, and for other salty alternatives, you can always have chicken or beef boullion.

Okay, it just occurred to me! You want CALORIE FREE? How about those cinnamon flavored toothpicks?

I know exactly how you feel, when I was a young' un my mum had these rubber curling things with a metal strip inside, I would cut the tip off, pull out the metal strip and just chew that rubber thing for hours, these days I tend to chew pen lids :-s
this is what the rubber things looked like:
http://i00.i.aliimg.com/wsphoto/v2/541377178/2-0cm-flexi-rod-for-font-b-hair-b-font-curler-color-sent-by-random.jpg