This was my second summer hosting purple martins. I had six pairs that nested. Out of the six, five pairs were successful.
I've learned a lot in the two years that I've had purple martins. They are unique birds with a very distinctive sound. I feel fortunate that they choose to spend their summer with me. I encourage anyone that has the right conditions for purple martins to consider putting up a martin house. In the eastern part of North America they nest almost exclusively in man made nest boxes.
The Purple Martin Conservation Association (PMCA) is a nonprofit organization dedicated to the conservation of Purple Martins. Their site contains lots of information about purple martins - from attracting and housing standards, to feeding and caring for orphaned chicks. The PMCA also has a great forum for asking questions or just posting your own experiences. Believe me, I've turned to the forum several times for help with various problems. I've always received quality answers from experienced personnel.
One other good purple martin reference is the Stokes Purple Martin Book:The Complete Guide to Attracting and Housing Purple Martins - I've found it very informative and turn to it often during the nesting season.