Reading a book yesterday and receiving an email from Amazon saying they cannot charge my credit card. While leaving the book open I clicked on the link in email, opened a browser, logged to my Amazon account and corrected the credit card details. Closed the browser, deleted the email and got back to the book. All that in a bus on the way to a pub without the need to wait to get to a computer or trying to use a crippled and slow browser in my old smartphone... Not a biggest WOW but a latest one...