Anyone know of a way using AJAX that I can use tp display some currency exchange rates on a site I'm building?
Use a site that has API to return currency rates preferably in JSON formats. Parse those and display on your site.
You may check out here.
You can make use of Google API.. here is an article on the subject:
But if you are ready to pay for a service, you might want to have a look at http://www.exchangerate-api.com/
You could also use Yahoo!'s currency service. They have a web-based API you can use:
http://uk.finance.yahoo.com/currencies/converter/#from=GBP;to=EUR;amt=1