NeMo is a high-performance spiking neural network simulator which simulates networks of Izhikevich neurons on CUDA-enabled GPUs, aiming for real-time simulation of 100 000s of realistically connected spiking neurons.
NeMo is a C++ class library, and also has bindings for pure C, Matlab, and Python. NeMo is one of the supported backends for the PyNN common simulator interface (in PyNN's development branch). SpikeStream can be used as a graphical frontend for the simulator.
A full range of download and support option (including a mailing list) can be found on the project development page.