Here's a bit of javascript that uses query strings. It parses the query string into a dictionary object called params, tests if a certain parameter was passed, and if it was passed it fills in a couple of input boxes with the passed values.
var params =;
  if (!(params.dt===undefined)) // Was the 'dt' param passed?
    $('date').value = params.dt;
    $('amount').value = params.amount; // assume the 'amount' was given

Thanks for reading! And if you want to get in touch, I'd love to hear from you: chris.hulbert at gmail.