Problem description:

What would be the easiest way to hold the high scores for my game without a hub?

The easiest way is to get a membership and use a hub, because it's all already handled for you.

If you want to do it yourself, you could use PHP/ASP/ect with a database like MySQL/SQLite to write a web server app that receives and returns scores.

This might be a good starting place:

You'll also have to find a free webhost that supports PHP and MySQL or SQLite. If you find one that supports only PHP, you may be able to just use file IO to manage the scores.
Damn, I only want this so that my GIAW's contest entry can hold high scores =( I have no $ XD
You could also do local high-scores, and just store them in a savefile.

You could use a free host or PHP/MySQL