I gave up doing this a few years ago, as it necessitated updates having to be made more or less on a daily basis, and in some instances I was never notified of those events that ended up being cancelled, so the listing ostensibly became irrelevant in the end.

What I have done is place a link on the front page of this website "Visitor Information"  with a link through to the section of the Government website - "What's On" 

In addition, here is a list of a lot of different websites related to what's on.

Public Transport - Bus & Rail What's On
Visitisleofman.com: http://www.visitisleofman.com/whats-on
Manx National Heritage: http://www.manxnationalheritage.im/whats-on/
Villa Gaiety: http://www.villagaiety.com
Isleofman.com: http://www.isleofman.com/events/
Isle of Man Guide: http://www.iomguide.com/events/event-list.php
Isle of Man Today: http://www.iomtoday.co.im/what-s-on
The best of the Isle of Man: https://www.thebestof.co.uk/local/the-is...man/events
Manx Radio: http://www.manxradio.com/community/
3FM:  http://www.three.fm/island-info