I want to talk briefly about stevia, aka stevia rebaudina to the biologists. You may already have heard of it, and if you haven't, you probably will soon.
Stevia is actually one of about 240 plants of the genus stevia, all related to the sunflower. It's a plant of South American ancestry, and it has been used for more than a century for one very important thing. It naturally contains compounds called stevioside and rebaudioside that are many times sweeter than sugar, with pretty much no calories. Yes, you read that correctly - it's an all-natural, low calorie sweetener.
So why isn't this thing all over the place? That's a very good question. There was one study done, back in 1985, which suggested that stevia compounds could be mutagenic (i.e. cancer-causing). However, and I want to emphasize this, no other studies have found such a link. In fact, in 2006, the World Health Organization not only cleared stevia of this sort of thing, but strongly hinted that it could have benefits for hypertension and/or type-2 diabetes. (If you have either of these conditions, check with your doctor before using stevia, please!)
Currently, its status in the USA is a bit odd - despite the fact that it should have "Generally Recognized As Safe" status (because it was in use before 1958), it can't actually be marketed as a sweetener in that country, only as a "dietary supplement". (There are conspiracy theories about why this is, but I won't get into them here.) However, new products are coming out in the near future from various manufacturers which incorporate stevia or stevia-derived compounds, including diet sodas and a "half-the-calories" orange juice. Its status varies in other countries. It's banned as a food additive in some countries, including Europe and Singapore, but used widely in others such as Japan and parts of South America. Here in Canada, we appear to be mimicking the US approach in calling it a "dietary supplement" - even when it's sold in the same stores as artificial sweeteners, it's usually not located anywhere near them, but over with the health supplements and protein powders.
You can buy stevia in two main forms - liquid extract (in a suspension of glycerin or alcohol) or powder. If you buy a stevia powder, read the contents carefully to see what it's "cut" with - if your stevia powder is pure then you only need a teensy bit for your morning coffee, so it's often cut with something like inulin fibre, maltodextrin, or rice starch to make it "spoonable" (one spoonful of stevia mixture is equivalent in sweetness to one spoonful of sugar).
If you decide to use stevia in any form other than the spoonable one, you'll need to know the equivalent sugar sweetness for baking and such. For example, many of the liquid extracts are so sweet that one tablespoon of the liquid is equivalent in sweetness to a cup of sugar. This is good if you're sweetening iced tea (for example), but can cause problems if you're using it for baking, as you may need to add something else to make up for the missing "bulk" of that cup of sugar. And, of course, stevia won't caramelize or "brown" in cooking or baking.
But, if you're looking for a sweetener that wasn't made in a laboratory and won't spike your blood sugar, you could do worse than taking a close look at stevia.