While many ideas discussed here require significant investment, here's something that any financial institution can do: Go green by supporting the environment through online banking via paper reduction, reduced trips to the bank, and so on.  

Some ideas:

• Plant a tree: We've seen several financial institutions use this one: A tree is planted whenever a customer signs up for estatements or electronic billpay. The latest to use it, Sovereign Bank and CheckFree today announced a program that donates funds to the National Arbor Day Foundation for setting up new electronic bills (excerpt below, see note 1). Their joint press release (here) contains good background info on the environmental impact of electronic delivery. Bank of America ran a similar promotion last year at this time (news release here, screenshot in note 2, webpage here).

As part of the Go Paperless campaign, developed to educate consumers
about the green-friendly benefits of paperless bills, Sovereign Bank and
CheckFree will donate $1 to The National Arbor Day Foundation for each new
electronic bill (e-bill) that customers activate at Sovereign Bank from
April 1 through May 31, 2007. Each donation will help cover the cost of
planting one new tree

• Green products: Australia's Bendigo Bank (banner above) and Canada's VanCity CU have entire product lines that encourage environmentally sensitive investment and consumption. Here's the lineup at VanCity:
• Clean Air Auto Loan
• Bright Ideas Home Financing
• Vancity Circadian Mutual Funds
• Shared World Term Deposits
• Shared Growth Term Deposits
• Enviro Visa
  
• Go carbon neutral: Several banks including HSBC and Bendigo have announced corporate initiatives to reduce carbon emissions or go totally carbon neutral by purchasing carbon offsets. Bendigo even allows customers to buy carbon offsets in its branches or through the mail via a downloadable form (here).
  
• Shredding days: This is the perfect springtime event. Invite anyone in the community to drop by the branch to shred sensitive documents, a great post-April 15 event as well. While shredding doesn't help the environment, other than recycling the results, one of the focuses of the event can be eliminating the paper in the first place through electronic statements and bills. During April, dozens of credit unions have shredding days planned, often in conjunction with other April 22 Earth Day activities. For example, Spokane Teachers Credit Union promotes "shred day" at its North Branch with this heading, "STCU helps 'shred' identity theft" (link here).

Note:

1. The CheckFree/Sovereign program is for e-bills, e.g., bill presentment, NOT bill payment. We missed that the first time through the release.

2. Bank of America's webpage discussing EarthDay 2006 promotion: