I once had a dream where I apparently had the ability to travel between alternate realities... so I'm in my house, going to sleep (In the dream itself, I only knew it was part of the dream when I woke up), I hear a loud knock on my door. I walk out and find myself in a messed up world that looks a bit like Zaphod Beeblebrox's mind on a drug-trip or something equally or more so bizarre.
I find myself easily able to navigate this world with ease, dispite its dimensional structure being totally different than our regular way of moving around a 3D universe. So then I try moving around it some and find myself unable to get back to the door because of some foreign logic that made it vanish when I got too far out from it.
I only managed to lock about half of the whole thing into my memory, but what I do remember had something to do with creatures from hell approaching me and consuming the world around me while I tried to find a way out. Basically, I was going "up" or toward some "Heavenly Light" or something, and I almost make it, when one of those creatures arrives and attacks me...and I wake up.
I had been a fan of Stephen King for a while, and had recently read one called the Langoliers, so that might have been where the creatures part at the end, and the "Heavenly Light" thing came from...