This rojo web applications seems worth to have a glance. It's a kinf of newsfeed aggregator/del.icio.us mashup:

Rojo is a FREE web-based service that lets you efficiently read RSS feeds from publishers big and small, ranging from millions of blogs to the New York Times. There is NO SOFTWARE to download and only Rojo (rhymes with mojo) offers ALL these features:

FEED READING & DISCOVERY. Find, track and read RSS feeds from millions of sources around the web, including major news outlets, weblogs, discussion boards, email groups, and ecommerce sites.

SEARCH. Search millions of RSS feeds for the latest news and information.

SHARING. The only social network for content, with Rojo you can connect with your friends and colleagues to help discover what you should be reading.

TAGS & COMMENTS. Tag and comment on stories for yourself and for others. Use others' tags to find stories that matter to you.

ROJO BUZZ. Find Recommended Links based on the feeds you subscribe to with Rojo's proprietary link analysis.

Why do I blog this? 'cause I am a newsfeed addict, that'y why I am always playing with tools related to it. This one is of particular interest (compared to bloglines) since it added the power of 'tags' to the exploring function (stories and feeds). It seems powerful, I am looking at it more carefully since it might be overlap our rss4you project (a francophone newsfeed aggregator that allows social navigation through RSS feed ratings).