http://howfastisthenbn.com.au/
It's a comparison of the broadband policies of Australia's two opposing political parties.
I posted it on the /r/Australia subreddit at ~4pm on a Tuesday and tweeted about it. 1.5 hours later the Minister of Communications and Broadband had retweeted it and then 30 minutes later the Prime Minister retweeted it.
Received 64k uniques between 4pm and 12am first day. 73k the next day after it was front-paged on the Sydney Morning Herald and news.com.au websites. Since launch I've had about ~186,989 uniques. Average time on site is 2:17.
At the top of the page are social sharing buttons for Facebook, Twitter, G+, and LinkedIn. The explosive growth definitely came from Facebook likes (58k) likes.
Lessons learned: NEVER make a website that doesn't have prominent social media buttons, and make sure your Twitter button has some worthwhile default tweet content and a #hashtag or two.
It was hosted as a Github page with Cloudflare in front.
Scrapes HN Who's hiring postings for internships. Eventually will allow arbitrary parsing by passing a function.
"ContUpt is a service, which reminds you regularly to contact your customers, users and friends."