* STINNER Victor <report@bugs.python.org>, 2011-10-19, 22:55:
>>FYI, in Debian we have at least:
>>one package using the CDROM module,
>Is it cdsuite? (http://offog.org/code/cdsuite.html)

No, Freevo <http://freevo.sourceforge.net/>.

>>3 packages using the IN module,
>I found policykit (it uses IN.INT_MAX).

Not in Debian, apparently...

>What are the 2 others? Which constants are used?

* Ganeti <http://code.google.com/p/ganeti/>: SO_PEERCRED;
* Mandos <http://www.recompile.se/mandos>: SO_BINDTODEVICE;
* Pydhcplib <http://pydhcplib.tuxfamily.org/>: SO_BINDTODEVICE.

>> 14 packages using the DLFCN module.
>
>Oh, so many? Which projects? Which constants are used?

* Boost <http://www.boost.org/>: RTLD_NOW, RTLD_GLOBAL;
* Ecasound <http://www.eca.cx/ecasound/>: RTLD_LAZY, RTLD_GLOBAL;
* GDCM <http://gdcm.sourceforge.net/>: RTLD_LAZY, RTLD_GLOBAL;
* GNU Radio <http://gnuradio.org/>: RTLD_GLOBAL;
* GStreamer <http://gstreamer.freedesktop.org/>: RTLD_GLOBAL, RTLD_LAZY;
* MPI for Python <http://code.google.com/p/mpi4py/>: RTLD_NOW, RTLD_GLOBAL;
* Open Babel <http://openbabel.org>: RTLD_GLOBAL;
* PyTrilinos <http://trilinos.sandia.gov/>: RTLD_NOW, RTLD_GLOBAL;
* SALOME <http://www.salome-platform.org/>: RTLD_NOW, RTLD_GLOBAL;
* VTK <http://www.vtk.org/>: RTLD_NOW, RTLD_GLOBAL;
* Yade <https://launchpad.net/yade>: RTLD_NOW, RTLD_GLOBAL;
* pyOpenSSL <http://launchpad.net/pyopenssl>: RTLD_NOW, RTLD_GLOBAL.

(That's only 12; we have two versions of Ecasound in the archive, and 
two binary packages with DLFCN-using code are produced from GDCM 
sources.)