It isn't exactly what you're looking for but it may be of some use to you. You can create your own Kindle formatted articles with anything from the Wikipedia website using the free Kindlepedia. I've tried it and it's very good
http://www.edukindle.com/downloads/kindlepedia
For other webpages/websites which I want to read on my Kindle. I save the page as an html file (file - save page as) and then I use MobiPocket Creator to make me a mobi file (Kindle) using the saved html. Bit of work but not that much.
Hope that helps and look forward to reading other people's ideas.