A few weeks ago I was thinking to myself, wouldn't it be great if my web browser automatically converted currency on foreign web sites to U.S. dollars? I thought briefly about trying to hack something together with Greasemonkey, but in the end I was too lazy, which is just as well because of course someone has already done it for me, though not with Greasemonkey. ViewMyCurrency is a Firefox extension and it does just what I've described: it automatically converts currency on foreign web sites to your local currency. If you want to see it in action, its developer has created a short screencast demo, or you can just download it. It works as advertised, with the particular caveat that currently it assumes all amounts preceded by a plain $ are U.S. dollars. Otherwise, though, this is supremely useful.