First of all, if you haven't heard of Tim Ferriss or his best selling book The Four Hour Work Week, you should read it. It is a solid read full of ready to implement ideas that will change how you think about work and time.
One of the biggest productivity killers around is email. People spend too much time on it. And Tim makes a great point that we all seem to think that we are the only ones who can handle our email. Rather than ask you to change, Tim lays out a complete process for outsourcing email, maintaining contact with those who are important and get this, increase human interaction all while freeing yourself from being a slave to your inbox.
If you've read his book, this post goes much deeper, he even gives you a copy of the rules his assistants use in interacting with clients to model, this is powerful stuff.
Read this post on Tim's blog now and even if you only implement 10% of it you'll save hours a week.