Hey man, thanks for being the first to dive in! I’m looking forward to how well this will develop over time. A metro-ish theme would indeed be right up NNF’s street.
Having the new thread / rss buttons on the side is pleasant. In the end they could have large symbols with smaller writing underneath, much as the Start Screen tiles on Win8, but that’s up to what you feel is right for what you’re going for.
As far as the competition is concerned consistency to your vision is important, so you need to harmonise a core set of values that you're aiming for:
* A clear layout that is repeated throughout
* A colour palette that you stick to
* A consistent means of displaying form elements and their interaction
* A typographical means of conveying information
For example, instead of just recolouring the title bars for sub-forums / threads, you could write the titles horizontally down the left or right side of the page; maybe even as a water-mark behind the threads, so that there wouldn’t be a need for the big blocky title bars themselves. Just an idea.
Looking forward to seeing more.
P.S. I hope you’re finding the code easy enough to deal with :)