On the NetTuts.com site they've posted a tutorial showing you how to build advanced features with IMAP and PHP. He bases it on the SimplifyEmail project and incldues examples of three different features to get you started.

Analysis of my own email showed I was receiving email from more than 230 automated senders, far fewer actual people. I was tired of constructing filters in Gmail and filling in a myriad of unsubscribe forms. I wanted to have more control over managing my email and simplifying my life. Finally, this past year, I decided to build the features I needed. The result is Simplify Email (SE), a small web app you can host yourself which offers a variety of cool new email features all of which you can check out on the project website. The coolest thing about SE is that it's a platform for reading, analyzing, routing and managing your email - the possibilities abound. Simplify Email is essentially a programmable playground for "hacking" your own email.

His three examples show you how to:

• Checking your inbox and filter messages
• Implement a Whitelist challenge to unknown senders
• Reporting unanswered email

Each of these comes with plenty of code examples, screenshots and output examples (as well as some places where you might need to change some SE configuration values).