Multiple currencies

Can we allow the visitor to select what currency they use preset by the admin?

For exampe, there may be online facilities which are targeted at Euroland so we would want to take Euros there or Dollarland so we would want to take dollars but local folk in the UK would want to pay in sterling. So the first categoriy could offer Euros or dollars as the preset (but also allowing a selection) and the second category could be preset to sterling with no option.

I don't think this is possible - if so perhaps it is a feature request!