When I hit a particularly annoying coding problem (I'm a web developer by day) I just walk away from the computer and look out the window for a bit.

If that doesn't work I go for a walk.

I solve writing problems on my daily commute watching the world and walking.

I think amphetamines actually increase my creativity alot sometimes. The way they do this is they create a drive in you which in extremes is basically like a manic episode. I used to be a bit manic depressive when I was younger and I was being prescribed Amphetamines for ADD and when I took them it definitely pushed me to manic extremes. The way I'd describe mania is having a bunch of energy and having a weaker mental filter so you will be bursting with ideas and have less of the doubt that usually keeps you from really believing in them.

So to sum it up manic or slightly manic states can help you come up with ideas and then I think when you are in a more rational mood is the right time to revise those ideas.