A collection of fun parkrun web apps below:

https://touristtool.mybluemix.net/

Find your nearest parkrun

http://www.challenge-chaser.com/map

A map that shows locations that would meet various challenges

https://wiki.parkrun.com/index.php/Club_Membership_(5km)_Totals

The number of people that have completed x number of runs

https://chrome.google.com/webstore/detail/running-challenges/kdapmdimgdebpgolimjnmcdlkbkddoif?hl=en

A Chrome extension that can be added to add extra detail to you parkrun results