An e-mail app I'm very much looking forward to is Mailbox. Only 60.000 people before me, but I'm patient. It looks like a good improvement to how I'm using email during the day. It will hopefully allow me to keep my inbox even cleaner from now on!
Mailbox has the nice feature to make email actionable. Something that goes well with the principles of GTD and 'Inbox Zero'. I only manually check my email because I absolutely hate notifications of any kind. Usually programs think they're more important than, oh I don't know, living my life, so I decide what and when I want to check up on apps and mail. Kind of narcissistic of these programs, right?
Anyway, taking control over email, making it actionable and most of all, manageable through a mobile device will most probably be a huge plus. The overall design aesthetics, a clean, minimal and logical interface, designed for swipe actions, satisfy my inner usability nerd.