You may laugh, but my favourite 100 cal treats are:

one oz. cube low fat hard cheese (emmental, farmers', mozzarella, etc.) with one large kosher dill pickle

Rye hard toast spread with small amount lobster paste, romaine leaf to fit, and skim milk cottage cheese heaped on top, all dusted with fresh ground black pepper

There's also a yummy salad (a meal, but can be split into good size hundred cal bowls) consisting of tuna, celery, apple chunks, pineapple chunks, skim milk cottage cheese (just enough to scatter curds through salad), onion, black pepper - you can add to this base. It needs no dressing because the cottage cheese and pineapple juice mingle to provide great flavour.

These all provide strong flavours with a hint of sweet, and are very satisfying. They also almost 'measure themselves', once you've prepared them a couple times, so you're not forced to go through the dismal routine of tablespoons and cup measures.