We had a roofing job done by Roofers "R" Us in September 2010. They provided all insurances and workers compensation papers upon request. They also had a strong reference from multiple people and at least one real estate agent (who had her own roof done by them as well!)
They came in for an estimate, and they were very honest. They tried to save us costs by reducing the amount of things that needed to be done on the roof.
In the end, their quote was one of the cheapest compared to 4 other roofers (we ignored some whose cost seemed too low and fishy).
After the job was done, they allowed us to go on the roof and they explained to us the work that was done. They were very informative and thorough. They cleaned up the property of garbage every day before they left.
I recommend everyone to use Roofers "R" Us.