I'm sure this is not entirely new and fancy for everyone, but it can be particularly helpful for anyone:
• entering contests
• RPing in the RP section of the forums

Why?
Most contests and [Advanced] RPs have word count requirements! It's important to check that you're within the requested boundaries before you submit an entry or a post.

This is my favourite word counter:

https://wordcounter.net/

If anyone else has other preferred word counters, note them in a reply and I'll add them to this post!