This is just a quick little tidbit. Out-of-Box workflows in MOSS, unless manually kicked off, require an event to be triggered. I was trying to figure out a way to automatically delete files from a document library 3 days after they were uploaded. The doc library was being used strictly as a transfer point and needed to be kept clean. Thanks to Sean S. for the idea...
So as simple as it is:
1. Start a new workflow using SharePoint Designer by going to File -> New -> Workflow.
2. Give the Workflow a name and select the target doc library or list.
3. Set the start event. I set mine to automatically start when the item is created or changed. Click Next.
4. Enter a name for Step 1 such as `Pause for 3 days'
5. Do not select a condition because we want it applied to all items.
6. Under Actions select `Pause for duration'.
7. Change to 3 days, 0 hours, and 0 minutes.
8. On the right choose to `Add workflow step'
9. Once again, give the step a name and no condition.
10. Select Delete Item under Actions and set it to Current Item.
11. Click Finish to save the workflow.
NOTE: A good way to test this first is to set the duration to a low count like 1 minute. Once you are sure it works properly, set it to your desired time frame.