A few days ago I posted a four-minute video from John Green talking about the UN's Millennium Development Goals, an ambitious proposal from the year 2000 to address a number of major world problems in just 15 years. You might have predicted the goals would not be met, and you would have been right. But the remarkable thing is (as Green pointed out in that video) how far we came. For more visit http://www.unmillenniumproject.org.
There's now a new set of goals you can read about at http://www.globalgoals.org. Here's a video created to promote them:
What's sad, predictably enough, are some of the comments. Evidently there are a remarkable number of creatures with access to computers who think that striving to make the world better constitutes "Communism," and who are hence opposed to doing that.
Update 2015 October 1: Since we don't get enough good news, you might enjoy this 2013 piece from Rob Wile at Business Insider on 31 positive trends. I mentioned it along with some related points in a previous blog post here.