Organize fields in the "Edit Card" window
Something like this: http://oi59.tinypic.com/sliq2c.jpg
Eric Lenington commented
Or even better, just a drag handle on the fields when they are in edit mode (or in the mobile app, a press/hold/drag, similar to how to rearrange icons on the home screen).
Absolutely agree. Using the separate popup window "Organize fields' is NOT user friendly as you don't see the fields' contents while you move them up/down. This should be done directly in the 'Edit Card' window as suggested.
Organizing fields is available in the Cards view, accessible via seperatly popup.