How to increment the document reference (not version) as the document is uploaded. Pre populate the column, so that when the next document is uploaded it will automatically have incremented in order. Trying to streamline a process for easier referencing/ease of searching.
Implement and deploy an event handler to automatically populate the “Unique ID” with a system-generated GUID after any “itemAdded” or "itemAdding" event using a feature.
Check this blog post out for detailed steps of doing it.
However in SharePoint 2010 its way easier all you have to do is Activate the Document ID site collection feature.