The snacks I have most frequently with me for between work and the gym or if I won't be geting home until late are bananas and fiber one bars (a box lives in my car for this purpose). Others easily portable snacks are baby carrots, fiber one cereal, various fruits, and cheese sticks.
Even things that need to be stored in the fridge are often fine for several hours at room temp. I eat applesauce with my lunches, and stuff like applesauce, pudding, and yogurt should be fine fora few hours at room temp, unless you prefer them cold.
I'm on the "Eat-as-much-as-possible-while-still-losing-weight" diet. It's working.