Forms with "Other amount" field should display a currency symbol with the field

At my organization I have received several phone calls from frustrated donors telling me that our website will not accept their donation because they have entered an invalid amount. This error happens when donors choose "other amount" and enter a value prefixed by a dollar sign. They're entering a dollar sign because the selectable options are displayed with a dollar sign and the field is not.

As discussed in this forum thread,
http://forum.civicrm.org/index.php/topic,27285.msg138769.html#msg138769
Civi should display a currency symbol before/after the field (where appropriate) so that users don't think they need to enter the currency symbol.