If you use labels to characterize your posts (and you should, it is a very handy way to organize your blog), you probably know how each label groups those posts together by category on separate label-search pages.
But wait, there's more.
You can list all of the posts with the same label in your sidebar, sorted alphabetically if you like, or in chronological order, oldest first.
For instance: All your recipes. Your 2010 trip to Italy. Your beer reviews. Whatever.