[smikolay]

Fred Wilson covers off the agregators he uses in the comments here, which might provide some inspiration: http://www.avc.com/a_vc/2009/04/celebrating-aggregation.html

While slightly different, the reddit code is here, and publicly available: http://code.reddit.com/

lastly, if you're looking for environmental news topics, I've slapped together: http://www.environmentalbubble.com/