Two of the biggest internet announcements this summer were J.K. Rowling unveiling Pottermore and Spotify coming to the US. It was expected that these websites would garner a large number of hits, but what is more interesting is to look at the severe dip in visitors each site experienced a few days after all the hype wore off.
Wolfram|Alpha provides graphs documenting the visitor histories of both sites, just simply enter the URL.
Both sites saw massive spikes followed by huge plummets (Pottermore more-so). This makes sense with Pottermore, as the site just recently allowed the first round of registrations more than a month after the site launched.