What's your nightmare cure?

I love this photo shot by my dad outside of the Paper Moon Diner in Baltimore.
 It reminds me of something out of a (good) dream

I spent most of today doing nothing. Yup, I had a very relaxing Easter Sunday, which consisted of avoiding homework, playing with my blog layout and napping. Unfortunately, because I spent most of the day playing the role of the immobile vegetable, I can't seem to fall asleep.  It's a few minutes after 1 AM and I can't stop thinking about my unstable summer plans, my many unfinished projects and the "fight" I just had via instant messenger. All of these things would seem much less daunting if they weren't bombarding my brain while I'm trying to sleep.

And I don't want to have nightmares again tonight.

Does anyone have any techniques for ensuring a nightmare-free sleep? I'm kind of sick of having dreams about getting asked to leave work, watching my new boyfriend (who unfortunately only exists in my nightmares) go off to war, and arriving to class unprepared.

While those are all annoying and stressful, the dreams I hate the most are about failed relationships. The dreams themselves aren't bad, in fact, they're usually quite good...until I wake up and realize that the guy is still a jerk and that he didn't actually ask me to go to that art museum on Sunday.

I'm pretty sure John Mayer says it best:

"When you're dreaming with a broken heart
  The waking up is the hardest part."

Now, my heart is far from broken, but still. Nightmares are not fun.

Any suggestions for curbing those pesky nightmares?