Steven Cohen is the Library List editor for PubSub which currently has a total of four Community Lists. A community list is essentially a blogroll, but augmented with some analysis provided by PubSub's LinkRanks tool. The analysis gives you a sense of the activity of the feeds in a list of sources. Also, I'm assuming the lists are easily turned into PubSub queries which generate an aggregate headline feed. With PubSub though, you could also get a meta-feed of posts that point to posts captured by the blogroll.
Some observations and thoughts. Since the analyses are dynamic, it would be powerful if they could be delivered as RSS. Similar mechanisms should be baked into webfeed aggregators. You could cobble something like this out of PubSub queries if there was a decent interface for managing and editing them.
I was about to blame this on PubSub's use of XMPP and lack of a Web services API, but there is no such lack. Apparently, I missed out on the PubSub REST API announcement. Conveniently this API deals with subscription management into PubSub and HTTP based distribution of announcements from PubSub. Wrapping all of this in a nice Web interface is just a small matter of programming.