Alltop.com is a web service which edits an aggregation of feeds on the most diverse subjects: for instance science.alltop.com is all about the top science feeds, while italian.alltop.com has every important feed from Italy. Alltop is an idea from Guy Kawasaki, a guy I admire because he was part of the first Macintosh produced by Apple, and because he is an intellgent entrepreneur and angel investor, one of those guys who finds and put money behind good (Web) projects.
Alltop itself is inspired by popurls.com, a similar service which aggregates popular feeds instead of topic-based ones, and allows for a certain degree of personalization.
I love both sites! For instance, check blogging.alltop.com! It contains everything a blogger (English-sepaking) may want top know on the blogosphere. I certainly hope Alltop will move to include also topic-based aggregation in other languages, which reflect other cultures.
One nice thing about the Alltop/Popursl paradigm is that it is a winning model for the diffusion of information. Thus, you can find Alltop-inspired themes for WordPress. And you may create sites such as this wonderful science aggregator: http://www.allsciencetopics.com/. It is all explained in this article: How to Create your Alltop/Populrs site for free with WordPress. This is also a conformation that WordPress is establishing a serious presence as a Universal Publishing Platform!