Argh, writer's block…always happens at the worst of times, huh?
Personally, the Shower Method works for me, but I've looked a little deeper into it and realised something.

Your mind only produces great ideas when you can't write them down.

Say, you're in the shower. Can't get near pen and paper or a computer…BAM! Great idea. If you're as scatterbrained as me, you'll have forgotten the idea by the time you get out of the shower.
Same for just drifting off to sleep (the time when you are scientifically least likely to feel like getting up again and writing) or in an hour-long car/bus/train journey with no notepad.
And if you carry a notepad around everywhere? The ideas don't come!

This is my advice. It might only be my mind plotting against me, though. :D

So freaking true.
Not only that, but I seem to have a problem where no normal period during my year is good for idea. When I'm at Uni, I'm busy, and when I'm on holidays, I'm either distracted by friends, or bored off my ass with nothing in the way of inspiration.