I got an e-mail today from someone who has just started a deliciously nasty blog about technology and the venture capital industry. When I asked if I could add it to my blogroll, the blogger said access was on an invitation-only basis. It got me thinking about whether private blog networks are possible in the age of search spiders. Then again, trying to limit access to your blog goes against the grain in a world of blog search tools, blogrolls, RSS feeds and AdSense.