I found this New York Times article on the Extra! Extra! section of NICAR.org and found it to be an interesting, compelling story.
The focus of the story was developed by looking at Armslist.com -- a gun-selling website that currently bypasses legal background check requirements.
The story begins with one specific case the Times found where a felon was trying to get a gun without a background check. The story uses clever multimedia options where readers can click text to get a picture of the specific postings from the website.
As the story continues, it discusses the 170,000 postings on Armslist.com -- a large data set. The writers and contributors likely used spreadsheets to analyze the postings and analyze them for trends and statistics. It is possible they wrote a program to help go through the site, but it is most likely they used more simple methods and put in a lot of time and effort.
The statistics and interactive graphics are effective because they take tons of information and make it relevant and interesting to readers. Everything is made more clear through their data analysis.