About six months ago I came across Huginn [1] for the third or fourth time and finally decided to give it a shot. I've absolutely loved it so far! The docs aren't always great for each agent, but I've never struggled for too long before figuring it out. I'm currently using it for:

* Scraping HN search for new appearances of projects I work on, and immedietely alerting me via email.

* Checking the frontpage of HN for topics I'm interested in, and adding it into my daily digest email.

* Pulling in Commit Strip and XKCD comics when they're posted and adding them to my daily digest email.

* Sending me a notification in the morning if it's going to rain.

* Giving me and my friends the cheapest flight price for a group holiday we're planning. It scans google flights daily so we can watch it tick down over time and decide when to buy.

* Sending me notifications if there's a significant drop in the currency for the country we're going to so I can purchase some at the best price.

* Adding the names of people who RSVP to my wedding into my daily digest email so I can keep a pulse on the final guest list.

Hopefully I'll get a few more ideas from this thread as well!

[1] Huginn - https://github.com/huginn/huginn