You have to be careful with Splenda though; for some people it still raises their blood sugars almost to the level of regular sugar. I've done some extensive research on this lately (as I'm one of those whose body sees it as real sugar!) and I've been lowcarbbing for the past few weeks.
What I've found for baking is there is a product called Erythritol at health food stores. It's a sugar alcohol but has the least amount of possibility to raise blood sugars of any sweetener out there. (well, except maybe stevia, but I dont' know if you can cook with it like sugar, and I think it tastes awful). It's about 75% as sweet as sugar so you may want to add a little Splenda in if you think it isn't sweet enough. It's also the best sweetener for baking. Comes in a granular form that looks just like sugar, and powdered. Powdered is better for baking unless you can dissolve the granular in hot liquid first. If not, you can make it powdered by running it through a blender.
I'll tell you though, it's difficult to find, but most likely to be able to find it at health food stores. DON'T confuse it with Xylitol, Maltitol, Sorbitol, etc. Those sugar alcohols can have a wicked effect on your stomach, especially in larger quantities like you would use in baking!! Erythritol doesn't cause any stomach upset because something like 90% of it doesn't get digested.
One downside I've found with it is it has a cooling effect in your mouth. Not like minty, but it makes your tongue feel cool. You get used to it by the second or third bite, and the effect is less the more of other sweeteners you mix in (like Splenda). Oh, and it's quite pricey too, but to me it's worth it to find a true sugar substitute that leaves no kind of aftertaste at all, and actually feels like sugar. I hope this helps!