This originally was a comment on mdlbear
's journal, but I feel it needs a wider audience, and expansion.
The problem with LJ is that the most useful factors - friends and communities, and granularity thereof - are not available on standard "plain" blogging software. Ordinary blogs are either/or - invite only, or all public. LJ has the granularity of access, but is controlled by a single corporation that is susceptible to economic and political pressure. What is needed is a way to build the community and friends lists (and access restrictions) that is platform and provider independent.
Enter "Blog Key". This software doesn't exist yet, it's only a concept. This concept involves a plugin. Each type of blogging software would have the plugin(s) ported to it, but is otherwise platform agnostic.
Plugin: "Blog Keys" - This plugin:
A) generates a public/private key pair, and integrates it into the viewing setting for your blog. No accepted key, no blog see.
B) provides easy distribution of public keys.
C) authenticates against given public key(s) that you've accepted, allowing the key generator(s) to read a protected entry.
D) provide an authentication layer by which you would be able to read the blogs of others who had accepted your key, and enabled you to read that entry.
E) provides rss feeds of blogs that you have keys to read (a "friends page")
If I want to be be involved in a blog key group, I enable access to my public key.
A blogger who want to let me read and comment on their blog transfers my public key to their plugin "Add my key!" type button. Thenthey add me to their general reader group, and additionally any subgroups that they wish. They would not, however, be able to read *my* entries, until I added their key to my plugin.
Essentially, the plugin becomes a keychain. I can read any journals that have accepted my key, and enabled my authenticated viewing of the particular entry.
Both commercial (6A) and open source blogging software could implement this. It would still allow public (no key required) posting, could be set up to require key authentication to comment, or be "friends only". All you'd need to participate would be a blogging platform that had the plugin available.
I can't program this, but I'm sure that an open project like WordPress would be glad to have it.