I first learned of Street-Complete here and I really like it.

It's satisfying to walk around, complete little tasks, and get prizes, scratching a similar itch to Pokemon Go.

Stuck waiting for someone? Add opening hours for a few local businesses.

Have a long walk ahead of you? See if you can add/check house addresses as fast as you can walk.

Want to walk off a few beers before heading home? Complete some tasks in the bar street.

Its a very constructive way to "be right" on the internet.