I've just published a new CodePlex project. This is a utility application to create sub folders each month in a document library. You can schedule this to run each month against a particular document library. It will create a top-level folder with a name like YYYY-MM where YYYY is the current year and MM is the month (e.g. 2008-07). The year and month are based on the current date.
The application then reads an XML file to determine what subfolder structure to create underneath the Year-Month folder. This can include any number of folders and subfolders. You can also specify custom security for a particular folder. Here is an example of the contents within the XML file
account="domain\my user name" access="contribute" />
account="domain\group name" access="read" />
account="domain\my user name" access="design" />
I'm interested to hear if others find this useful and whether people have suggestions on how the application can be improved. The project is available at http://www.codeplex.com/WSSCreateFolders. Check out the other SharePoint related CodePlex projects – there is some fantastic stuff available here