[iamhenrychung]

Well to start there's:

Reddit (http://reddit.com)

Boxnutt (http://boxnutt.com)

Snipit (http://snip.it)

What others have you guys came across?

[SuperChihuahua]

Dont forget: Trejdify - business news only (http://www.trejdify.com/)

Inbound - SEO/marketing only (http://inbound.org/)

[prplhaz4]

Not simple aggregation per-se, but http://dev.newsblur.com is showcasing a much more intelligent approach to social news discovery...

[jeffchuber]

Completely self-serving - but I do see my project playing into this space. http://knowitapp.com