Believe it or not, there are things in life sweeter than sugar, and also a whole lot better for you.
Yacon syrup - awesome choice: uber low GI with a maple-syrup taste. Expensive, however, so I use it rarely.
Inulin/chicolin - a fructooligosaccharide (FOS), it promotes good bacteria in the intestines. Not too sweet, however (more like fiber than sugar), and can cause bloating/gas in excess
Stevia - way sweeter than sugar, but has a very narrow threshold of sweet-but-not-too-sweet. Too sweet with stevia = bitter and disgusting. So, always add gradually by taste. Comes in liquid and powder forms- though liquid may tend to "bake out" of things.
Agave nectar - relatively low GI. Taste is light and very sweet, and very versatile. It's my go-to sweetener. Hopefully you can tolerate it!
Brown rice syrup - also has a dark-but-neutral taste. Good substitute for molasses; also is very viscous, and seems to lend a (tar-like, but in a good way) flexibility to rolled cookie dough.
Barley Malt - I've never used it in baking, but it IS in my favorite Sunspire grain-sweetened chocolate chips! It is indeed low GI. WARNING: is not gluten-free.
Erythritol - made from beet sugar, it is a zero calorie sweetener that is natural and low(/no) GI. Its production does require some processing, so I held out a long time before trying it. It works well for me though! Has the AMAZING property that it can be POWDERED in a food processor, and thus used in frostings and glazes. Also has a cooling property in the mouth-- you know how mint tastes "cool"? It's like that.
Xylitol - kinda like erythritol, except with more cooling effect, possibly a little less sweet, and also more likely to cause some lower-intestine indigestion. But, good for your teeth!
Coconut Sugar - Basically, this IS brown sugar. Only really really good for you. It's pretty dang awesome!!!
Yacon Powder - Kinda stinks. Not really sweet, and just adds a funny taste. Someone please tell me when this is useful, instead of just messing up baked goods by pretending to be powdered sugar when it's not?
Vegetable Glycerine - Ahh, the glycerine days... this was my baby baby baking days, when my mom was the Chief Baker and I was the poor salad-eating girl at school. But the novice became the master, and I have moved on to bigger, better, more powerful sweeteners!!! ... ... vegetable glycerine is uber low GI, and mildly sweet. (I have a great pumpkin bread that uses it!) You may have to look in the massage section to find it though... no joke!
Raisins - yes, they sweeten. Especially in RAW BROWNIES!!!
Dates - sweeter, darker, and more aromatic flavor than raisins, plus add more kick for less volume/fiber than raisins.
Vanilla - good for a minor kick of flavor + sweet.
Bananas / Fruit / Applesauce / Fruit Juice- Don't forget about them! They can be a wonderfully healthy way to add sweetness and flavor to baked goods, smoothies, puddings, etc. Remember that their sugar is fructose (mediocre GI, so use in moderation), and that fructose gets less sweet when baked. The GI fructose-factor is, however, balanced by the nutrients that whole fruits give to the finished product.
Truvia - Erythritol + Stevia blend. Thus, as long as some processing of the natural ingredients is okay, this works!!! Hooray, put it in your hot tea, and drink like a normal human being!!