These are the experts with plenty of information about setting up and maintaining a bluebird box or a series of bluebird boxes, called a nestbox trail.
Site includes research bibliography about bluebirds and other cavity nesters.
Here is another great source of information about bluebird boxes and other cavity nesters from the Audubon Society of Omaha, Nebraska. Their web site also includes links to the songs and calls of bluebirds, nestbox plans and many pictures. Here is a good article from the Wisconsin Department of Natural Resources magazine that explains why and how to leave dead snags in woodlands. This online pamphlet from the US Fish and Wildlife Service includes suggestions about how to attract different birds, bird box dimensions and information about protecting nestboxes from predators. The Wildlife Habitat Council encourages corporations to improve the wildlife habitat on corporate campuses.