Marking e-mails with ink
How many times do you receive (long) e-mails that you keep in your inbox because you want to return to them later, e.g. to check one of the links that was included? Problem is, anytime you do go back to this message, you have to read everything again because you don't remember anymore WHAT it is you wanted to check later. Here's where siple inking would come in handily. Let the user mark the section of the e-mail (s)he want to check later.