Bluebirds are very beneficial birds that consume a lot of insects. They have become largely dependent on us to provide housing and habitat for them, and it's very easy to do so.
It's easy to build a Bluebird nest box. The plans are on this website. Build several and look around for places to mount them. Cemeteries, ball fields and large yards are possibilities, but be sure to get permission.
After you've mounted the boxes, be certain that you check them frequently. House Sparrows will try to move in and will even destroy the Bluebird eggs, so be vigilant and keep the sparrows out. I've been at war with one House Sparrow that is almost as stubborn as I am! As soon as I take the nest materials out he puts them back in. I have a feeling it's going to be a long spring and summer for the two of us!
For a while, no birds (other than my sparrow nemesis) showed any interest in the nest boxes. I had Eastern Bluebirds for a while, but after a cold front moved through, they seemed to have disappeared. They recently returned, however, and are building nests. Tree Swallows have moved in to some of the other boxes. Since Tree Swallows are also beneficial birds, I haven't disturbed them.
I am hoping that the Eastern Bluebirds and Tree Swallows will be successful and return each year. I'm also hoping that the House Sparrow gives up sooner rather than later!