C'mon man. There's a post just a few below this asking the exact same thing.
http://forums.studentdoctor.net/showthread.php?t=932194
But for what its worth, I have never seen a "sample" LOR posted on SDN, but people like
LizzyM has given a rundown of what a basic letter includes and there are several "how to guides" out there on the internet. Search google or search the forum and you will find more than anyone will ever post in this thread.