Password entry field with CapsLock warning and chroma-hash indicator
A specialized field for password entry, working as a drop-in replacement for TextField in "secret mode" (extends TextField both on the server and client).
Shows a warning icon (with a descriptive tooltip) if the user types in the field while CapsLock is on.
Shows a "chroma-hash flag" to help the user catch typoed passwords - a password with a typo will not produce the same "flag" as the correct password.
Features can be turned on/off and customized in a number of ways.
Tested browsers marked, though the others probably work as well (note that the current default CapsLock warning icon does not work well in IE6 due to transparency).