The Meaning of Life, the Universe, and Everything.
Overall, I am LOVING the beta forums. The only small thing I have noticed is that when (on at least Mac OS X) you hover over the "View the markup" button, the whole toolbar gets pushed to the right. This is definitely not a big bug, and it may not even be in your control to fix, but it does cause a slight cosmetic error that slightly annoys me. See the screenshots below (very hard to see, but the whole toolbar is shifted over a little when the [BB] button is selected). This, again, only happens with the "View the markup" button.