Okay, in rebuttal to C.I.'s unlinked source, here's some others. Most just refer to studies without actually linking to them, but some are citing some pretty heavy duty stuff.
Does any of this prove the existance of God? Yes, to those who have experienced God. No, to those who have not. But anybody who is the least bit objective has to allow for the possibility that there just might be something to it:
Here's one site of which I know nothing about or the organization that produces it. But they cite an awful lot of studies that could probably be traced. I do know about the UNM study here in Albuquerque but have not seen what analysis they came up with.
http://1stholistic.com/Prayer/hol_prayer_proof.htm
This one is perhaps from a more verifiably credible source (I'm not saying the other one isn't credible but I can't verify that it is.)
http://www.theunion.com/article/20051007/TODAYSFEATURE/51007006
Healing Through Prayer: Health Practitioners Tell the Story
by Larry Dossey
ISBN:1551262290 (More details...)
Publisher Comments:
Prayer really works! In this unique book doctors and patients quote scientific surveys and relate personal experiences of healing with prayer. They are convinced that prayer has had a profound effect in their lives. Although they do not try to explain how prayer works, many refer to a greater power ?-?- some say God ?-?- who enables the healing work of prayer.
These interviews and stories will provide new conviction to people of all religious faiths, and will give new hope to those who seek healing for themselves, for others, and for the world
http://www.powells.com/biblio?PID=719&cgi=product&isbn=1551262290
Doctors increasingly find introducing prayer helps calm patients and speeds recovery
By Raymond McCaffrey
The Gazette
http://www.texnews.com/1998/religion/med1003.html
MORE STUDIES CITED
http://miraclesofprayer.com/pages/research.htm