When the Nintendo Wii were released, they were extremely hard to get. Even months later, sellers including Amazon would run of of stock almost as soon as they got them in.

WiiMe's tweets

A few lines of ruby code, querying the amazon e-commerce API (determining if the Wii was in stock), if so, tweeting it out twitter.com/WiiMe ~ archive.org...

I got a Wii. I also helped a few hundred other people get theirs. I was happy to see Twitter co-founder Ev Williams share his love of it :)