Dutchies released a nice dark theme called Dutch_itis
Here are some features:
1. Left or Right block can be of (change in theme.php)
2. Forum, coppermine or Shoppincard are displayed in full with (no
blocks)
3. Nsn banner aware (otherwise default banner module is used) displayed at the bottom of the theme.
The zip contains 2 versions one for PHPNuke 7.x the other one is for Platinum
7.60 (extra forum mods)
Demo
Screenshot
Download