Yeah, I know... it's kind of slow for what it does...
Right now the Nanohub version only runs simple single-band effective mass ballistic simulations. These simulations have been done hundreds of times before me - and you can do it yourself in MATLAB, if you follow the excellent tutorial of Supriyo Datta, Superlatt. and Microstruct. 28, 253 (2000).
BUT: The underlying engine ANGEL can do much more than that. It has an MPI-parallelized energy space to be able and calculate the k-dependence of the Green's functions explicitly (unlike in the nanohub tool). It has all sorts of scattering mechanisms inmplemented. It can couple an electron and a hole band. So in essence, it;s really cool!
So this Nanohub tool is really just a teaser for the paradise of possible simulations that awaits you when you install ANGEL on your own supercomputer and run it in parallel!