FedEx's website lets you set a password of unlimited length (I've tested it up to 100), but when logging in, the password field has a maxlength of 25 characters, so it'll reject your >25 character password. If you override the maxlength in the HTML and enter the full password, then the form complains that the password field is empty.
@waldoj Have you ever considered a career in QA or pen-testing? Because this "I must now test exactly how far I can push this bug" mindset is common to both.
@mogul I push the QA and pentest folks. :)