I was discussing alternatives to sugar with one of the people at the new T on Fairfax (in the Fairfax district of LA) because they carry stevia and agave nectar in addition to honeys and cane sugar. I struck up a conversation with Josh (he's there in the mornings) about how great it was to find places that even thought to include such alternatives. The difficulties of baking without using sugar came up, and he mentioned that VEGETABLE GLYCERIN (you know, the kind available in the cosmetic section of a natural-foods store) worked. I haven't tried it yet, but I definitely will. It shouldn't affect the flavor like molasses and honey, and it definitely wouldn't make it as mushy as they would either.
My old stand-by was simply to cut the sugar content of a recipe (things in this country are too sweet anyway) by at least a quarter (up to half) and to use brown sugar, which has more humectants. This vegetable glycerin thing might work though.