A little nit-picky thing I have with the USPS's choices are their add-ons for tracking: USPS Tracking (end-to-end), Return Receipt (proof of delivery), Signature Confirmation (update to date tracking and proof of delivery) & Certified Mail (allows receiver to track delivery).

WTF - these are barely differentiated and only confuse people who don't mail things often. WWSJD (Steve Jobs) - probably have a single add-on choice he'd call something like PackageKit which would be $2 and include up-to-date tracking (for buyer and seller) and proof of delivery.