My friend and associate at Origin Entertainment, (and Act One Alumna!), Vicki Peterson, has formally started a service to read and critique scripts for writers at all levels. I have been using Vicki for over a year now to read and evaluate projects, and she is one of the best that I've worked with. She is very pastoral with writers, helping them to say better what they have to say, as opposed to trying to make every project in her own image and tastes.
Go here for more info about how to enlist Vicki to get your script to the next level.