In his recent post about the My Jeeves, Danny correctly points out the differences between AJ and a9 allowing you to save, store, and search your personal results and tools like Eurekester that offer the user the chance to personalize or "reshape" their results.
Another company doing work with "personalized" content is Seattle-based Findory. Greg Linden and his team offer a product that delivers personalized pages (the service offers a search option) of news based on your past clicking and reading behavior. You can also have a personalized newspaper delivered via email. Findory technology powers Blogory which offers the same type of thing for weblog content. Blogory also offers an "adaptive" RSS feed.
In June, Chris provided an overview of Findory in this SearchDay article.
Finally, make sure to take a look at this blog post where Greg Linden offers his take on the differences between customization and personalization. I find them very useful.