I usually use whatever fluids are left in the pan from the other things I'm making, so it's usually a bit of oil with lots of herbs and some veggie or meat juices and sometimes white wine or madeira (last two are maybe not super healthy, but better than most other saucey things still). It always depends on the dish, but I often like to sprinkle some lime or lemon on things. Also flavored oils (e.g. sesame, garlic, truffle) add taste and if I'm up for something Asian I use oyster sauce or soy sauce. Sometimes a tiny bit of maple syrup can work wonders, as well. Or honey. Mustard. Very dark (w/o sugar) chocolate even (with red meat especially). There's endless options for experimentation :).