For all OpenBabel users: I have updated the Wiki page on how to compile 
OpenBabel on Windows using MinGW:
http://openbabel.org/wiki/Install_(MinGW)
The resulting DLL (libopenbabel-3.dll) may be linked directly from 
Windows applications using MinGW, so there is no need to deal with 
(import) libraries created with Microsoft Visual C++. This is especially 
useful if your existing software uses a GNU make based build system. 
Binaries created with MinGW are native and do not need an emulation 
layer, such as Cygwin.
Regards, Andreas