This summer Bo Yang, a student at NanKai University in Tianjin, China, worked on a microsummary builder extension. His goal was to make it easy for regular users to create custom live titles for pages while experimenting with some additional features for power users.
He's recently uploaded the extension to addons.mozilla.org, and I've created a screencast showing it in action. Check out the screencast, then try out the extension (Firefox 3 pre-releases or nightly builds only).
Don't forget to file any bugs you find, and let Bo know (in comments on this blog post or by emailing him directly) what kinds of pages you're summarizing and how the extension works for you.
(For example, I used it to create a live title of timeandate.com's World Clock page showing the approximate time in Bo's time zone so I knew when I could expect to see him online.)