Indie authors, united

With the current explosion of self-published books, it's never too early to start thinking about promoting a book. Just like anything else for sale, there are many ways to go about doing this. I've started putting together a marketing plan for mine.

While doing some research (aka Googling), I found an interesting blog post by M G Edwards about Wikipedia and its treatment of indie authors. Edwards also happened to mention some good sites for indie authors, two of which I'm familiar with from other sources.

They are:

• The Independent Author Network (I'm familiar with this one but haven't signed up yet)
• World Literary Cafe (signed up a while back but haven't been very active)
• Independent Author Index (no experience with this one)

Which indie author groups do you like, and why?