Instapaper.com is one of those tools that isn't very flashy but is oh-so-useful. Think of it as a clipping service, or maybe a temporary bookmarking service. You drag a bookmarklet to the Favorites bar of your browser, and then when you happen upon an article you'd like to read later (in fact, that's the name of the bookmarklet: Read Later) you click the button and the article is saved to your Instapaper page.
When you have some free reading time, you head to Instapaper.com and there you'll find a list of article titles you've saved. Click a link to read the article and at the same time that link is moved to an "Archived" section, removing it from the main page (this behavior can be turned off). I've been using Instapaper for quite a while, most often when my RSS reader gets backlogged. I zip through articles, quickly hitting "Read Now" for stuff worth more careful perusal later. Fast, simple and easy.
And now Instapaper has gotten better! Many thanks to MG Sielger at TechCrunch for pointing out the new additions, since Instapaper didn't make much of a fuss about them. Three major new features have been added to Instapaper. First, there's a new bookmarklet that forgoes a tiny pop-up 'Save now" window for an inline notice in the top left corner of the page you're viewing. Second, you can now set up folders to help organize your saved articles. You have to go to Instapaper.com to file articles, though. It'd be nice to have the option of sending them to a folder when you save them (though that would make saving articles a 2-step process). Lastly, you can now check out the "Starred" items of other users, giving Instapaper a light social feel. See the Instapaper blog for more details.
All of these features feel very 'lite' which is important, because the simplicity of Instapaper is what makes it such a valuable tool. Oh, and it you're an iPhone user, there're a pair of Instapaper apps: a free version and a $10 'Pro' version (currently on sale for $5) that adds a few bonus features. Both versions will save your articles for off-line reading. You can get details on the iPhone apps here. The web version of Instapaper is free and definitely worth checking out for anyone needing a way to help organize their web surfing.