Does anyone know where I can get my hands on any Marvel or DC comics tryout scripts? (For artists.) Or even any published scripts? A google search turns up only one useful sight by Dwayne McDuffie, but I’m hoping to find more.
Okay, without googling, which would most likely just return information you’ve already attained, I’ll try to be helpful.
Though they haven’t issued a recent one, Marvel has two “Marvel Try-Out Books” which I believe provide sample scripts. It is my understanding that Marvel has discontinued this practice of talent harvesting.
Search the Marvel website (marvel.com) or read any of the “'Nuff Said” issues put out roughly a year ago. Each issue had a few snippets of the script in the back, showing what the artist received. That may help you more as interpreting a silent script may show off your ability to convey movements and emotions.
I do not know so much about DC practices, but last I checked they had information for submissions. Perhaps this includes a sample script. DC.com should have any informaiton on that.
If you want to write an original script with established characters for submission purposes, find a basic template for scripting a comic (crossgen.com has a fairly good one) and write out five pages (on artboard, that is) of script, and then draw out your idea.
If you need a sample script with established characters, just e-mail me. 
I can get one to you in a couple minutes. I’m currently finishing my scripts for a considered property.
There are two by Steve Gerber on his website: http://www.stevegerber.com/
One is for Howard the Duck and one is for Sludge.
Offline, there’s a SANDMAN script by Neil Gaiman in whichever anthology has “Calliope.”