Please, develop a visual stand-alone debugger for your OpenCL implementation.
Something like NVIDIA's nSight, but don't integrate into Visual Studio... it's better an OS-portable standalone app ( made in Qt or similar ) so we can use in linux, MacOSX, etc... with minimal effort.
I'm specifically interestered in placing breakpoints and inspecting variables.
Other things I use ( but less times ) are "run to cursor" ( skipping the execution of several lines ahead/backwards ) as well as variable-modify-value ( alter the variable's value manually at runtime ).
You could also add a command line one for the command-line lovers although I would really prefer a visual one.