Adding a Description Column for a folder under Document Library

• Go to Site Actions, Site Settings
• Click Site Content Types
• Click Create
• Give the new content type a name such as "Description"
• Set the parent content type group as Folder Content Types
• Set the parent content type to Folder
• Add the new content type to a Group. I put it back in the "Folder Content Types" group
• Click OK
• Scroll down to the columns section and click Add from new site column
• Name the column and set all the usual column options
• Repeat for any additional columns
• Click OK
• Go to your document library
• Click Settings and Library Settings, or in 2010 click the Library ribbon tab and then click Library Settings
• Click Advanced and set Allow management of content types to Yes and click OK (this may already selected)
• Scroll down to Content Types and click Add from existing site content types and add your new folder content type
• Go to your document library and click the New drop down, or the New button in the 2010 Document ribbon, and add your new folder!
• Go to the View drop down and click Modify this view and add your new folder meta data columns (you will probably want to move them to just after the Name column)