Found this and thought it was an excellent idea. The Robin Hood Tax is a tax on bankers that would raise billion by taking an average of 0.05% from speculative banking transactions. That means the 'casino' trading that is overwhelmingly responsible for the current financial crisis.
There does seem to be some concern that banks would simple pass these costs on, but it still seems like a good idea.
You can find out more at robinhoodtax.org.uk