Workflow: Reminder Before Due Date – MOSS vs. WSS
How to create a workflow that reminds you a week before an item is due. This item could be anything in SharePoint, such as a document or task. In the example, I’ll use a task, and the built in Due Date field.
SharePoint Workflows – Linking to Workflows in List Views and Item Displays
How to place a link to a Workflow on the display form of an item. Also covers how to put the same sort of link as a column in a list.

Via Enterprise 2.0: Culture Is as Culture Does. The Enterprise 2.0 Deployment and Adoption Workflow, depicting different routes of Enterprise 2.0 projects.