Where are big samples?

Hi,
Where I can find free big samples of drawings: dxf,dwg or dgn? Especially geospatial data.
I found http://www.bim-architecture.com/support-idea/dwg-3d-models/

big and small assorted DWGs:
http://cben.net/

DGN files:
http://dgnlib.maptools.org/dl/dgnsamp.zip

A good manual for GIT:
   http://www-cs-students.stanford.edu/~blynn/gitmagic/book.pdf

Online version, other formats, translations, source code, etc.
   http://www-cs-students.stanford.edu/~blynn/gitmagic/

Thanks Rallaz

This info is really useful for me -especially the Cad Block Exchange Network link.