So you want to participate in the challenge, but don't have a blog? Not to worry you can still participate.
The linking system I'm using can't be used without a link, but you can use other links if need be.
I recommend not submitting a Facebook link or any that is to a private profile, but if you're on something like Twitter you can submit that. You can also submit a link if you're on a social network like GoodReads, Shelfari, or Booktagger, as long as you link back to the shelf or list if you're able to. If that's the case head on over to the Century Challenge page and enter your link.
Non Social Networking
Don't have a social network account or blog? Just post a comment with your name (or a nickname) and let us know what challenge level you are doing. You can also come back and let us know where you're up to and how you're finding the challenge. You can do this by simply posting a comment again, but I recommend posting a reply to your submission comment instead.