Elevator pitch is much like headlines when it comes to coming up with one, deleting them, practicing them again and finally applying.
I like testing it on a website and use an elevator pitch as a headline or sub-headline, and measuring the effectiveness by tracking response.
What I do is create a squeeze page based on different elevator pitches and split test them to see which one generates greater response.
I wrote an article on creating an effective elevator pitch a while ago. May be it will add some ideas.
http://ezinearticles.com/?Crafting-Your ... &id=290693
One thing I tell myself whenever needing to create a new elevator pitch is I try NOT to dwell on my qualification, credentials, experience so much -- that part is done as my prospect once opts in to check out the freebie resources.
But I try creating something interesting so that it will elicit them to want to know seek more than the initial contact.