Okay, here's a bank that's doing something positive.  Yes, they're based in the UK, but they have on-line banking available to all.  The GREEN part is described at their Corporate Social Responsibility page http://www.hsbc.com/hsbc/csr

Their goal is to be "Carbon Neutral" by the end of 2006.  They are in the process now of an independent audit to determine if they reached that goal for the last quarter of 2005.  What is carbon neutral?  Basically they determine how much carbon they're using in their business process (heating buildings, flying people around, etc, etc) and they contribute to organizations to get an equal amount of carbon avoidance (e.g. alternative (non-carbon based) heating, trees to replace deforrestation, etc, etc)

So, if you're not happy with your current bank, maybe check out HSBC at www.hsbc.com 

Just want to calculate your annual carbon use?  And maybe off set it?  Look at http://www.carbonfund.org  I'm still looking into their non-profit stats (e.g. what percent of donations go to supported funds vs executives)... but at least you can check out their estimate of your carbon foot print.  Unfortunately, they don't have the ability to account for farm vehicles, but at least you can get an idea.

Kami