Does anyone know of any successful (that is, profitable) subscription-based web sites?

I've think I remember reading somewhere that the Wall Street Journal's web site www.wsj.com is a profitable subscription-based web site....

I suspect (but I'm not 100% sure) that www.stratfor.com is probably another profitable subscription-based web site....

On a smaller scale, I believe Bill Myers' Idea Bank was also a successful subscription-based model....

If you know of any more that you think are profitable, I'd be grateful.... :)

I'm interested in this because there only seem to be a few things you can do for an online-only business (with no physical products at all).... Such as sell ebooks or online music (selling online movies has to come eventually too), sell software, sell advertising, online auctions, or selling subscriptions....

I believe that selling subscriptions will become much bigger than it is now, but what works online is still being figured out.... With everything being given away for free, selling subscriptions has so far been languishing (with a few exceptions), but I believe that selling highly specialized information in a subscription format does seem to work....

Thanks for any feedback!

- Dien