I've had a few friends ask me about using News Aggregators. I'm also in the process of pushing the use of blogs & aggregators at work as a piece of the KM suite. For a primer on aggregators, take a look at Morgan Wilson's overview. Scott Hanselman also has an interesting write-up. My take: I've tried a bunch (NewsGator, AmphetaDesk, FeedReader, NewzCrawler and NetNewsWire on a Mac) but I always come back to Radio Userland. I use Radio to manage my blog but even if I gave it up (and I am actually thinking of giving MovableType a go, or I may wait to see what TypePad has under the hood) I would continue to use Radio as my aggregator. I find the presentation of feeds in a single browser window far more efficient than having to click around three panes (which is how most of the others do it).
I am currently subscribed to 134 news feeds This is a lot, but with Radio I am able to "consume" these sources 2-3 times a day. I could never "consume" new content from 134 websites multiple times each day. This is the power of RSS and Aggregators.
I'll try to post a detailed desription of my aggregator surfing habits, which I think are pretty well optimized, within the next day or so.