I use currency conversion through Google when I travel a lot but one currency I never thought to convert was "proper money." A search for [1 USD in proper money] converts $1 US to British Pound Sterling if you are searching while in the UK but when you search in the US, it gives you Euros. If you search in Australia, it gives you the Australian Dollar.
Try it yourself...
Searching in the US:
Searching in the UK:
Searching in Australia:
Forum discussion at Google+.
