Evernote's Web Clipper is a fantastic way to save select parts of an article, but it's not really useful unless you use Evernote. If you'd prefer something simpler, Gloss allows you to highlight and save text from any site quickly.
Gloss is a bookmarklet that lives in your bookmarks bar. When you want to save a line from an article you're reading, hit the Gloss button, and select the sentences you want to save. These are then stored on the Gloss site where you can glance at them whenever you want.
The lines you save also have a couple sentences around them so you have context, but you can always click back to the original article if you want. Similar services, like the aforementioned Web Clipper, Findings, or Diigo have been around for a while, but Gloss is one of the simplest solutions.