I feel like the next employee hired needs to be a designer and usability/user interface expert.
Some things on the site are ugly and not usable at all.
Like for example, when you track a file rather than that box popping up with tiny little X in the corner, it should just be a simple toast notification, could appear under the button or in a corner of the page, but rather than requiring complete attention, it would be simple and the user would know right away that it worked (colors would help with this, the bubble that pops up is green, it worked, red would be an error, then the person could look at the text to investigate further.)
Here I did a little mockup to show what I mean (and I'm no designer/UX guy).
https://www.dropbox.com/s/xeyerd6qkctf9v9/nexus-ex1.jpg
I think a few small improvements like this would go a long way to making the site smooth and more professional feeling. Right now it doesn't seem believable 5 guys work on this site.
This all being said, Nexus sites are great and I want to support them so I've added a filter to my add blocking.