Boost.Compute (https://github.com/kylelutz/compute) - A C++ GPU Computing Library for OpenCL

It's cool because it offers C++ developers an easy path to running code on GPUs and multi-core CPUs via an STL-like API. It's similar to NVIDIA's Thrust library but supports all OpenCL compatible devices (including AMD GPUs and Intel CPUs/accelerators).

Documentation is here: http://kylelutz.github.io/compute/

P.S. It's still under active development and we're looking for more contributors with an interest in parallel computing and C++. Send me an e-mail if you're interested!