Compile OpenBLAS for R on Windows
Install MinGW using the installer:
http://sourceforge.net/projects/mingw/files/latest/download?source=files
Make sure install MSYS
Install wget within MinGW: mingw-get install msys-wget
Download OpenBLAS:
https://github.com/xianyi/OpenBLAS/archive/develop.zip
Compile it using make