OniBrowser allows you to view Oni data files.

Some keyboard shotcuts:
Level view
B - show grids
D - show doors - broken
T - show textures
O - show octtree
F - show furniture
P - show ghosts
N - show collision
I - show invisible
L - show vertex colors
F5 - show flags
F6 - show sounds
F7 - show trigger volumes
F8 - show current BNV

In the Tools\Options set the path to GameDataFolder

Requires
.net 4 framework: http://www.microsoft.com/en-us/download/details.aspx?id=17113
XNA 4 framework: http://www.microsoft.com/en-us/download/details.aspx?id=27598