Archiving script

I need a script which will auto-move files over x days old from one directory to another one, but I also want to create directories along the way. The files to be archived are phone call recordings in a call center, so there are soooooo many of them. The file names are typically formatted like this: [login to view URL] [login to view URL] [login to view URL] There are additional formats as well. BUT, every file name contains a datestamp, i.e., "20110630" in the above examples. As the files are moved to another directory, I would like them filed into folders and subfolders by year and month, i.e., /monitor/2011/06/30/ and to keep the original filename as it is moved. The source folder contains ALL of the files to be examined for moving to the archive folder. The resulting bash script will need to be called via a cron job to run every night and we will want to change the number of days used as criteria for moving the files. Right now, we want to move anything to the archive directories over 180 days old, but that may change in the future. Full documentation of script is expected as well, i.e., tell us how it works so we can tweak it ourselves in the future.