I frequently find a long article while browsing the web for something else that interests me, but I just don’t have the time to read at that moment. Instapaper was designed for this problem. One nice feature is that you don’t even have to sign up to use it: it can keep track of your list of articles based on cookies in your browser. If you plan to use it from more than one browser, it is quick and easy to sign up for an userid. The developer of the site said he was motivated because he wants to encourage people to write longer articles for the web.