In what kind of instances do you use it?

Whenever I want to read articles or text, but not on my computer. Either because I want a distraction free environment (no tabs on the Kindle), or because I won't bring my laptop with me, or because I'm outside and need a glare free screen, or because I prefer the soft light of the Kindle screen late at night and in bed, etc., etc.

My most recent sent-to-Kindle article is this one. If I like it, I will import it into my Calibre library and tag it as "read" and maybe "thinking" or "creativity" or some such. As an alternative to bookmarking or Evernote web-clipping.