The NYC Open Data initiative has dumped a ton of New York public records--school test scores, court districts, even laundromat maps--on one website. But the site is not exactly what you'd call "explorable." A "Showing 10 of 2118" pages, with a next button nearby, looms large on the bottom of the site.
Enter designer Chris Whong, who created a parallel site that serves as a visual guide to all that open data. Whong's site presents assorted branches that break down the data into categories, all viewable on a single page. So hover around the "Social Services" branch, and you'll see dots representing data for homelessness, high school graduation help centers, and more. Here's a close-up:
Click on one of the dots, and it'll take you to the data source on New York's government site. The symbols on the dots represent how the data is tabulated--whether it's a table, map, or something else.
It's still nearly overwhelming (so many dots!) but at least it makes the absolutely monstrous amount of data viewable at a glance. Which is good, since if you look at the visualization for long enough, you'll occasionally find a gem, like this not surprisingly thin map of parking spots in the city.