It uses the Links table and will accept any columns you want, so by default you have:

Title, Description and the installer adds a Price column so if you wanted you could add a few more custom columns to the Links table and turn those records into the advertising options....so you could add "Impressions" or whatever, then you can inserts the appropriate tags into the templates and people can purchase advertising.

Currencies aren't currently handled but I guess it could be done with a simple global like:

Total in USD: <%Total%>
Total in CAD: <%Plugins::ShoppingCart::convert(Total, exchange_rate)%>

I'll add in the convert routine if that looks like it may be useful.

Edit: Thinking about it, you could just do:

<%Total / exchange_rate%>

I *think*