As many people have already commented, Dave Winer has re-created his OPML-sharing tool. You can upload your OPML file for people to see who (and what) you subscribe to. I can't imagine the general population playing with this.
About a dozen people subscribe to my various feeds, and I know about half of them by name. Of those, I've met one. Hi Doug! FeedBurner says I have about 700 subscribers.
Of the "subscriptions like mine," I notice a gentleman who has 8000 feeds in his OPML. And there are a bunch that have over 1000 feeds. I'm guessing the participants are on the upper end of users. I've got a mere 352 feeds.