Ask HN: What things would you like to track?

An open question to the HN community. If you wanted a website service to alert you when something happened, what would you want to track? I'm thinking kind of Siri like service, but it only notifies you when things happen.

For example, here are a couple things I might track:

+ When the next Jason Mraz album comes out + When it reaches 40 degrees at 2am in southern california + When a crime occurs within 5 miles of my home

etc.

What would you guys/gals want to track?