I'm a big fan of CCC.orgs!
However, considering there are still about 20% of them available, you should focus on registering domains with meaning (like 49k, v36, etc.). If you can't find any names with meaning, you should try to go for names with repeating characters. For example: 9bb.org (which is available at the moment).
For now, your domains are worth reg fee, but once every CCC.org has been bought out, the value of all of them -- including yours -- will rise.