1. You've been staring at your desktop client and/or dashboard for a very long time, asking the same question over and over: "What to blog? What to blog? What to blog?..."
2. You have a bunch of half-started blog posts or mile-long blog ideas. But, not really blogging them completely.
3. You've been posting re-hash entries from your other web activities (Twitter, Facebook, Flickr, etc) - for weeks on end.
4. You just link, link, link and/or quote, quote, quote. Nothing new to say. Nothing fresh to add.
5. You just want to blog to meet quotas/make money/give in to people's demands... Blogging has just become a chore, a job, another thing on a "to do" list.
6. You've lost your will/energy/time to read other blogs. You don't comment. You don't join any conversations or community efforts.
7. You've become overly obsessed with stats - how many comments, page views, back links, ranking, subscribers, Diggs/Stumbles... And, anything less than what you hope for/expect just get you down.
8. You ignore comments on your own blog.
9. You've forgotten why you wanted to blog in the first place.