Since I'm on a five-star metaphoric kick, I wanted to mention a Five-Star widget NetFlix provides both on their site and in HTML-emails for customers to rate movies they rented.
There aren't many cool web-based widgets in the world, but this is one of them. Their email and web versions differ slightly, but both work with one-click efficiency. Find the star and click it. Actually, Amazon has a five-star widget that fills in the stars as you move your mouse over it like NetFlix, but it was the ease in entering a review in an email that made me sit up and take notice. Another smart move on NetFlix' part was to prominently list the “Rate This DVD“ in the “We've Received [the DVD]” email.
(Riverdance was Five Stars, by the way.)