Edamame is one of my go to snacks, I tend to prefer salty over sweet so it's a good option. I also keep a small container of veggies cut up in the fridge, when I just want to nibble on something with a bit of crunch it's great to have it all ready, right now it has celery, green pepper, yellow pepper, cucumber and carrots in it.
If I do find I want something sweet I usually blend up a smoothie, it's filling and if done right quite healthy. The one I had this morning was mango, banana, macadamia nuts, cardamom and some vanilla almond milk - I won't claim that one was really low-cal though but it was still healthy and filling.