I practically live on Twitter. Jen's Butler is an interactive Twitter bot that allows me to do nearly anything without leaving Twitter. The butler can access online services I use, retrieve files I store locally on various computers, and control connected devices in my home.
The butler accesses services in two different ways. Most of the functionality comes from the Python script that generates the tweets. This script also calculates astronomical predictions, works with local files, edits images, controls security equipment connected to a Raspberry Pi, and many other actions. The rest of the functionality comes from IFTTT such as providing sports scores.