Shared Items on Google Reader

I am playing around a bit with Google's shared items capability, which is available from Google reader. Here are my shared items, still fairly sparse. You can set up a feed for these shared items as well. It forms a blog of items you choose to share with your friends. Though you cannot add your own comments. If you use the Google Reader RSS aggregator, it's sort of a friends network. I am still trying to understand how this scales. I have friends that aggregate into different groups ... professional friends who are interested in topic X, family, etc. Can I categorize them when I share? Check out the reader blog for more. I would like to see some examples of how people are using this usefully.