Filtering YouTube videos by creation date, analyzing tweets of users included in a certain list, searching strictly by one subreddit - there are hundreds of examples of using them.
- live maps (weather, fire, clouds)
- historic maps (worldwide, countries, towns)
- local conflicts and disasters maps
- satellite maps
- ability to upload your own maps
If you look at a person's history of posts on social media, you can gather a lot of interesting info about them. One of the simplest way to automate this:
Save the feed of posts in PDF (using the Ubikron ext or others)
Process PDF with different online tools (summarize etc)
A repository with text files containing a million dorks for finding potentially vulnerable web pages and sensitive data (in Google and other search engines).