I think more board colors should be added.

It would be great if the board color could be expanded, like if the user could choose any combination of colors within the normal RGB scale thing. Expanded textures would be really great too, but probably not as necessary.

That would be sweet!

It's been thought about, but isn't high on the todo list. You can try editing the page for yourself with something like tampermonkey (Google Chrome) or greesemonkey (FireFox) to change the styles of the page in a persistent manner.