I have nightmares a lot, too. They used to be so bad and frequent that I would not sleep until exhaustion forced me to, and I had periods where I would refuse to sleep at night time because it intensified the nightmares (I felt very vulnerable and paranoid at night).
I have nightmares about a variety of things, some of them really, really weird. I've had ones where I'm kidnapped by people and violently tortured - a distinct one I remember is one where my kidnappers hold me in front of a mirror and with a scalpel begin to cut and then peel off my skin from my body, and force me to stare into the mirror.
I have a lot of them where it's dark and I'm out in the streets, and I have to run and run to get away from some people that I know are trying to catch me and kill me. I run through the streets and see horrible things happening everywhere I look; I see girls being raped, tortured, killed.
I have some where it's like I'm watching myself, as if through a movie. One I remember was watching my then-boyfriend bury my own dead and disfigured body.
Like you, I've also had dreams where I re-experience times of my life. It's as though things take off from a certain point, and nothing that had happened had ever actually happened. For me, this is where I dream that my mother still lives with my dad, sister, and I, and that my parents never actually divorced. My mother is an unstable and violent/abusive person, and my parents' divorce was the best thing to have happened for me, so these dreams are rather horrible.
I also have ones that scare me in a different way - ones where I'm carrying out horrible violent acts against the people I love, my pets, and random strangers...
Then there's the plain old abandonment phobia ones - where my fears of abandonment come true in my dreams, my friends tell me they hate me and then cut me out.
A lot of the time when horrible things happen or are happening in my dreams, I become incapable of moving, or if I can move it's so slow and sluggish, like I'm moving my legs through air that's a million times denser than real air. It creates a horrible feeling of powerlessness.
Sooo, yep, I get bad dreams too! Oddly, Valium helped me a lot (I was either dreamless, or I could never remember them when I woke). I can't have Valium anymore though, unfortunately.
Something that might be of particular interest to you guys is the concept of lucid dreaming, or at the very least dream awareness like Beautiful Disaster mentions. I used to be able to do it when I was a kid, but I guess I've kind of lost the knack.
http://en.wikipedia.org/wiki/Lucid_dream