There are plenty of ways and means of getting things onto your Kindle that don’t come from the Amazon store. Emailing to yourself (although I’ve never managed to get that to work) and using the experimental browser, and other such methods allow you to read things that don’t take the form of a book.
I am enjoying a site recently recommended to me, though, that combines the best of both worlds - Readlists. Not-for-Kindle content, in the form of a book. Readlists is an experimental page for now, and it comes from the people behind the social reading app Readmill. It allows you to collect together content from webpages, bundle it into a book and read it later.
You simply copy and past the various links into the site, hit bundle, and it sends you an email with your ebook attached. I actually haven’t tried it on my Kindle, but tested it via the iBooks app and it was brilliant. If there’s a particularly long article you want to read, or one that covers multiple pages - perhaps an online story you want to devour at your own pace - then this is a great way of doing it. You can also share the lists with others, and the site itself has featured and recent lists to browse through.
Interestingly, this is one of those solutions that I find brilliant despite the fact it had never really occurred to me as a problem needing solving. It’s just another way of adding functionality to your ebook readers, and devouring even more great content.