NaCl OpenGL example
So far, it appears that NaCL (http://code.google.com/chrome/nativeclient/) doesn't allow you to do peer-to-peer networking, but by looking at the API you can start with this, which will enable you to work with URLS, and get a response:
http://code.google.com/chrome/nativeclient/docs/reference/pepperc/struct_p_p_b___u_r_l_loader.html
For 3D example you can look at the code here, which will at least show you what functions that were used.
http://src.chromium.org/viewvc/chrome/trunk/src/ppapi/examples/gles2/
I was trying to find the answer for this one a few days ago.
Here is a working NaCl OpenGL cube webpage
Here is the code for the sample you can compile "out of the box" like the other NaCl SDK samples:
BTW: I renamed the .nexe files to .n - to stop an annoying Chrome warning about the files.
Here is an example of Ogre3D sample browser:
https://chrome.google.com/webstore/detail/ocpoapiejnpokdojkgjhglijajghikla