Sgt_Kickaxe - 11:55 am on Jan 2, 2013 (gmt 0)
I have category pages with no headings which serve up a different header image based on topic, the heading would be redundant and I noindex,follow my category pages so I suppose that's one example.
I also have had a long running site use H2 tags for the heading and not have a single H1 tag on the page, it ranked well anyway. I don't even remember why I switched to H2 tags but undoing it now would mean finding the handful of pages it would break first, there are a few H1 tags scattered in older posts, and it's just not worth the time and effort to fix, imo. Perhaps when it nags at me a little I'll bump it up my to-do list.