Tom Murrell's "Secrets of Email Marketing"

This is a short (one and a half minutes long) video stressing the importance of customer retention -- turning a customer into a client. Some interesting statistics are presented to demonstrate the bottom line advantage to retaining a customer.

Almost incidental, considering the video's title, is a nod to how effective e-mail marketing can be to maintaining client contact.

For more on difficult customer check out The Defusing Hostile Customers Workbook.