It all sounds lovely doesn't it? However, when you dig deep down in the system, where's this money actually coming from? Taxing money as it bounces around the financial system is all well and good, but it's got to get in there somewhere, so it's not entirely removed from our savings and loans, etc.
What gets hit then? The obvious thing that springs to mind would be the banks profits, which I certainly wouldn't object to. However, as with any other corporation, the banks main purpose is to make profit, so they will obviously try to recoup these losses from somewhere. Where?
It would be lovely to think it would hit all the bankers wages and bonuses, especially given public feeling towards these at the moment. However, bankers don't get paid large sums of money because they deserve it more than highly skilled workers in other sectors, or because the banks like giving them large sums of money. In fact, the banks would probably like to pay them as little as possible in order to maximise profit, but need to pay in accordance with the market rate in order to retain the staff.
In the end I suspect most of the cost will end up being carried by the people, whether through increased bank charges or through increased costs of products from other corporations as they cover there increased costs. If you want to do the real Robin Hood thing then use an income tax to tax the rich to raise these funds. Anything else will tax the poor too, which isn't very Robin Hood.
OK, it would raise a lot of money, which could be used to help with a lot of issues within the world, and in the process give us all a clear conscience while we live in relative paradise compared with much of the rest of the world. Given that at the heart of many of these major issues lies consumerism and the hording of resources and property, and it's the monetary system that actively encourages these activities, surely it would be better to address the issue at this level?
The greed of the banking sector is a massive wound on our society, you can't just fix it with a sticking plaster.