1) Local events finder. A few friends of mine and I moved from San Francisco to Los Angeles last year and didn't know many people. Even though there is a vibrant event scene down here with hundreds of events every day, we always seemed to find out about the cool ones after they had passed. I wrote a Facebook scraper that would find all of the local businesses and events for each of the businesses. It puts it in a Postgres database and then does some simple sorting based on different signals (e.g. how many likes for the page, how many people RSVPing yes, maybe, no for the event) and spits out a spreadsheet. This has been great to discover events and a huge time saver for planning dates.
2) Photo organizer. I use Dropbox's iOS app to backup photos from my phone to Dropbox. However, it just puts them into one big folder. I wrote a simple Python script to parse the filenames of the photos/videos and put them into a nested folder structure by year/month.
3) Long flight movie digest. I had a few long flights that weren't going to have wifi, so I built a web scraper to pull the movie list from the flight ahead of time and then cross reference it with Rotten Tomatoes so I could get a stack ranking of the movies by Tomatometer rating.