I always like carrying some form of sugar-free candy in my purse as a safety measure, to ward off hunger. The Myntz and Sqyntz come in nice metal tins which keep the mints fresh. They use sorbitol as their sweetener and have 0g carbs.
We brought the green tea Myntz with ginseng on our driving trip around Europe and LOVED them. The whole car of us - two low carbers and two non low carbers - ate quite a few of them. They have a light flavor and give you a bit of pep. Ginseng is a nice bonus!
The Sqyntz is a newer find, a tropical fruit blend with vitamin C. Perfect for wintery flu-filled times! These come in 3 flavors. Pink is melon, green is kiwi/lime, and yellow is pineapple/melon. All three are nice and sour, great for sucking on.
I highly recommend keeping a tin or two in your purse or around the house. They have zero carbs and if you're caught somewhere that you can't get to real food, they help keep hunger at bay until you get to your next meal!

Lisa Shea's Library of Low Carb Books