That are SUPER low cal (and relatively healthy!) that one can eat to stave off a bit of hunger between meals?

Peanut butter. 100 calories/ tbs quick, easy, yummy and satisfying

First make sure you're not thirsty by drinking a big glass of water.

Cup of soup or broth (usually less than 80 calories and the heat can satiate for a long time).

A carrot and a glass of water. For me something that's crunchy and takes a while to eat is most helpful. The fact it's fibrous seems to give my stomach something to do LOL.

Well, most veggies are low calorie in general... But for more flavorful options...

Spinach or kale with a bit of balsamic vinegar (approximately 75 calories per cup)

Canned tuna with mustard instead of mayo inside a cucumber boat (approximately 110 calories for whole can plus cucumber)

Baby Carrots with plain greek yogurt (approximately 100 calories for 10 carrots plus 1/2 cup yogurt)

Chicken, vegetable, or beef broth (approximately <= 80 calories per cup)

Pistachios (approximately 100 calories per 30 nuts)

edamame is good-- another good for a chocolate fix and I know it sounds wired but it really is good: 1 cup fat free ricotta cheese, 1-2 tablespoons cocoa powder (more or less depending on your choc hunger), 1 teaspoon vanilla (or to taste), 1 or 2 packets splenda--again depending on your taste...80 calories 1/2 cup

That doesn't sound gross at all, it's actually KIND of the way i lost 100 lbs. i had to replace my daily chocolate fix (usually daily 1/2 lb bag of M&M's at least!) so i do a nightly cup of 30 cal almond/vanilla milk with 2 T dark cocoa powder, stevia to sweeten and a guilty dash of flavored creamer such as irish creme heated up to make hot cocoa

I do turkey sandwiches. I use Sara Lee 35 calorie bread and turkey breast. Comes in at 120 calories

Seaweed!

Smoked kippers.

Pickles are one of my favorite snacks, too.
I also like radishes, pepperoncini, and plain arugula.

And I don't worry about counting the calories for any of these. Instead I usually pat myself on the back for choosing one of them instead of some of the other choices available in my kitchen.

I eat pickled everything. Brussel sprouts, garlic, beets, onions, quails eggs, herring, jalepenos you name it. I like the way pickles keep and they are almost as good nutritionally.

Hearts of Palm. Hmmmm so good. Low cal like 15 cal or so.

A couple of boiled eggs works for me.

Purred vegetable soup keeps me full for hours and mine are 75-150 calories per cup.