I've seen the green rim in Jotun's post numerous times -- like a spark, brief and subtle, when watching sunset over an ocean horizon. (even some times when we weren't drinking! LOL) and a close friend has seen it once at sunrise in the Caribbean. Though I've never seen the sky go green -- yet -- I'll keep watching.
Interestingly, I've also been told that it's more common further north, due to the lower angle of the sun's rays. OTOH, I'm not inclined to sit out in my parka on a windy shore any longer than I have to ;-)