The choice is not big, but there are a few interesting themes out there
With Halloween just around the corner, perhaps you want to customize your Google Chrome to be in tune with the holiday. Unfortunately, there aren't that many Halloween themes for Chrome, though a couple look rather interesting.Funnily enough, perhaps the best looking Halloween theme for Chrome is not even available in the Chrome Web Store.
It's dubbed Happy Halloween and it looks pretty snazzy. You can grab it here.
If you're wary of installing themes from somewhere outside of the Web Store, you still have some choice.
The appropriately named "Halloween theme" isn't that bad looking, but there are better alternatives. For example the "Black magic dead zombies" theme, which definitely cranks things up a notch.
If you're looking for something more peaceful and playful, the simple Halloween theme may be for you.