Send to Kindle is for text-oriented web pages you see on your PC that you want read on your Kindle. I use it at least a couple times a week for longish news articles and essays, as they are more pleasant to read on my eInk Kindle than on a PC.
Here's one I just used Send to Kindle on:
http://www.foreignaffairs.com/articl...-long-division
No endorsement of the above link is intended, as I have not yet read it!
It remains true to me (and few others) that eReaders are only slightly superior to books over paper, but far superior for essays. And old link, suitable for Send to Kindle, that I do endorse:
http://blogs.telegraph.co.uk/news/da...is-for-essays/