I needed one that would let me read later offline.
Readability, at least, does this, and does it extremely well! I can even send the article to my Kindle app (in my case, on my iPad) with one click!
Readability also, like the other services, makes it cleaner to read sans ads, etc.
Check it out!
If you opt to add the bookmarklet buttons to your browser, there is one that saves to your online archive, one that lets you read now, and one that sends the article immediately to your Kindle reader (or Kindle app)!
This image is taken from the front page of the Readability page - it shows that the service can be used on a wide variety of devices (due in part to Kindle compatibility).
This is a (partial) view of the interface when you access it online. You can keep current and archived articles, mark some as favorites, subscribe to favorite article publishers / authors, and even send specific articles to friends, etc.