Twylah is one of the services which aggregates Your Twitter audience and sorts it into topics - mostly used as semiautomatized or fully automatized newsletter.
There is also service called paper.li which provides you with connections to RSS channels etc.
Some of the twylah pages are important to read, some not. Many people use it to make week reviews. It is useful not only for public, but also for Yourself, because twitter is really quick and many articles are posted when we sleep for example.
If Somebody wants to make overview of their twitter account (about what they are passionate), twylah is the way ;)