It's been three years since I last went through my inbox to unsubscribe from the marketing and information lists I no longer read. At that time, I still used email to keep up on ecommerce and banking news. Now, that task has moved almost entirely to RSS, and I rarely read any broadcast email these days. 

During a two-hour paring process to delist 40 to 50 subscriptions from email, I paid close attention to how each company handled that bit of negative news and jotted down a few best practices for banks, credit unions, and other financial providers (note 1): 

1. Put your branding on the unsubscribe page, don't simply default to your email service provider page.  
2. Greet the customer by name and/or email address.
3. Provide customer testimonials on the value of the email subscription.
4. Empathize with their situation (e.g., Getting too much mail?), but reiterate the benefits of staying in touch with you (e.g., We really want our customers to get the best deals!) and gently see if you can change their minds (e.g., Are you sure? Try us for another month, and we'll do our best to bring you only pertinent offers.) 
5. If that fails, offer alternative ways to maintain contact, for instance:
   - Less-frequent email (see first screenshot below)
   - RSS feed(s) (see second screenshot below)
   - Better-targeted email on just certain subjects
   - Use a different email address
   - Change email format (HTML vs. text)
   - Use SMS instead of email
6. If applicable, explain that customers will still receive account-related email messages.
7. Provide a feedback form so users can tell you why they are unsubscribing.
8. Confirm the request online and provide links to other areas of your website.
9. Send an email confirming that the unsubscribe process is complete.

Step 1: TigerDirect unsubscribe page (20 July 2009)
Email subscribers clicking on "unsubscribe" are first asked if they'd prefer to receive fewer emails.

Step 2: After unsubscribing, customers can sign up for RSS or catalog delivery 

Update: Staples...another good example of offering choices on the main unsubscribe page (screenshot 22 July 2009; hat tip to Loren McDonald, note 2):

Notes:
1. U.S. emailers must comply with CAN-SPAM regulations at all times. 
2. Here's a good presentation from Loren McDonald from Silverpop on the subject. 
3. For more info on email marketing, see our Online Banking Report on Email Marketing in Financial Services (published June 2006).