I want to perfect my web development skills. What's a neat thing I could make, which would require me to learn a new (and important) skill?

I'm no webdev (or any kind of dev, for that matter), but a little chat application is always how I learn a new tool/language; it requires a little bit of pretty much everything your need to become proficient in a technology (networking, database manipulation, data representation, etc.), while also being a common-enough thing to build that there is usually a good number of documentation/tutorials out there if you get stuck.

i'm usually really bad at thinking of things too, but how i typically learn something new is by taking on something that is way too big for a personal project and diving head first into the docs for the technology i want to learn.

i think a better answer though is find an open API you like (see a giant list here: https://github.com/public-apis/public-apis)) and maybe make an app where you can do some basic stuff like filtering, searching, pagination, and if you're feeling bold, some CRUD operations. Like maybe a trash can icon that will remove something from a list or a form to add something new. I think those are all fundamental skills you're going to end up implementing at whatever company.

That's a great idea! Thank you for the suggestion.