Back in 2011, housing market in Rio de Janeiro was booming and it was very difficult to rent a house or apartment.
Every time I found a nice apartment, even if it had been submitted a couple hours ago, real state agencies would not accept my submissions, as they had already received a dozen submissions.
So I had to be faster. I built this application using Ruby (and Rails, just for ActiveRecord and ActionMailer) which, also using Heroku Scheduler, looked up on Zap Imóveis - a popular real state website in Brazil - for new apartments in the area I was looking for. If there was a new item on those search terms, it would send me an email.
It was also the first time I used Nokogiri.