The Moosehead Vegetarian cookbook is supposed to be great, I have yet to add it to my collection.
One of my favorites is The Carb Conscious Vegetarian by Robin Robertson.
My other favorites are anything by Rose Elliot, I bought her books here in the UK.
I would suggest reading reviews on Amazon.com, thats how I buy many of my books.
Accentuate the positives, medicate the negatives ~ Amy Sedaris