I love NextStories.com, it presents an attractive picture of the web as an open-ended, free-flowing continuous thematic newspaper.
For example, a reader could be reading an article on Mashable, hit the bookmarklet (once installed), and be presented with similar articles from sources across the web, from a pool that currently includes about 100 tech blogs. There’s no subscription or registration process required, and NextStories doesn’t need a user’s personal information to work, since it’s looking at content they’re already browsing for clues about what to serve next.