This may be usless to anyone who bakes on a regular basis, but for those of you that would rather cook than bake...this tip is for you.
A while back I read in a cooking magazine that if you kept your brown sugar in the fridge, it would stay soft. I tried it in a Tupperware, but it took a while to soften up once I took it out of the fridge. So I tried a Ziploc bag instead. Works beautifully every time. I just pull it out and give it a squeeze. The brown sugar is soft and usable. On the same brown sugar note, if you have hard brown sugar and you want to salvage it without heating it up, you can grate it with a cheese grater.