otherinbox.com
What: Helps organize your inbox by arranging emails in categories (for known email marketers) and helping you to manage your subscriptions (no longer need to go through the hassle of removing yourself from mailing lists for which you have subscribed or never subscribed)
Why: Email management is a problem for sure. There are multiple solutions that try to address this problem in different ways such as Shortmail.com that allows you to write short emails (inspired from Twitter) and others. Reducing any sort of redundancy and junk and increasing work force efficiency by managing emails better is in huge demand - certainly Otherinbox.com is working in the right direction.
I Like: I love the subscription management feature.
I Recommend: There are few things that I would like these guys to do better:
Privacy & Security: It is not clear for me how they manage privacy. I am essentially giving them access to my email. How do they ensure that my trust won't be broken and no one will get access to my emails
Templates: I would imaging that this is on their roadmap if not already present. Basically, I am writing lots of emails with similar content - would help if I can have template feature for such emails.
Enterprise Play: It will be very interesting to see how they would approach SMB's. For that an integration with Outlook Exchange is important too!