(From MMikami 000929)
Crystal Lattice Structures Database 
   http://cst-www.nrl.navy.mil/lattice/

   From the page, 

   This page offers a concise index of common crystal lattice
   structures. A graphical representation as well as useful
   information about the lattices can be obtained by clicking on 
   the desired structure below.

(From MMikami 020110)
Mineralogical Resources
(from Mineralogical Society of America, http://www.minsocam.org

1-a) Software (http://www.minsocam.org/MSA/Software.html)

1-b) Mineral-related links (http://www.minsocam.org/MSA/Research_Links.html )
     "Mineral Databases" section is one of my favorite, in particular,
     Mineralogy Database (http://webmineral.com/) give us detailed
     explanations with pictures of many crystals.
     
1-c) The Crystal Structure Database
     (http://www.minsocam.org/MSA/Crystal-Database.html)

(From AOganov 030207)
Bilbao server for Crystallography
http://www.cryst.ehu.es
Contains symmetry information and k-vector notations for all the 230 space groups

(From RCaracas 030320)
Crystallography Open Database
http://sdpd.univ-lemans.fr/cod

(From MMikami 030718)
EMS OnLine
From "Info" page ( http://cimesg1.epfl.ch/CIOL/summary.html ):
"EMS On Line implements some features of EMS (Electron Microscopy Image Simulation), the commercial 
software which is developed by Pierre Stadelmann at the Center for Electron Microscopy (CIME), in 
Lausanne. About 20 of the 70 sub-programmes of this package have been linked together with perl 
scripts for make them accessible on the World Wide Web."

If one enters the next page by clicking the "Run" button,
one can find the crystal database: the user library has "2885 crystals saved by users of EMS
OnLine." But kindly notice that "There is no guaranty of correctness !!!"


American Mineralogist Crystal Structure Database
http://www.geo.arizona.edu/AMS/amcsd.phgp

(From MMikami 030812)
- WARNING : in french -
JAVA Applets for space groups

http://www.univ-lemans.fr/enseignements/physique/02/cristallo/cristal.html
http://www.univ-lemans.fr/enseignements/physique/02/cristallo/espace.html
http://www.univ-lemans.fr/enseignements/physique/02/cristallo/stereo.html


(From MMikami 041026)
A good On-line Lectures for "Structure of Solids" 
by Prof.Stephen J. Heyes (http://www.chem.ox.ac.uk/icl/heyes.html), 
in particular, "Structures of Simple Inorganic Solids"
http://www.chem.ox.ac.uk/icl/heyes/structure_of_solids/strucsol.html
See also the online "practical":
http://neon.chem.ox.ac.uk/course/inorganicsolids/
(NB: He also writes "Chemistry of Lanthanides and Actinides":
 http://www.chem.ox.ac.uk/icl/heyes/LanthAct/lanthact.html)


"Crystal Structures" by Prof. Winston Chan(http://home3.netcarrier.com/~chan/)
http://home3.netcarrier.com/~chan/SOLIDSTATE/CRYSTAL/
Prof. Chan has written Java applets to allow you to view and manipulate crystal structures within your web browser. 


"Software database for crystallography" from Laboratoire de Minelogie-Cristallographie
http://www.lmcp.jussieu.fr/sincris/logiciel/


NB: the above pages are traced from a useful URL list:
http://chemistry.about.com/od/crystallography/

(From A.R.Oganov 041027)
ICSD(Inorganic Crystal Structure Database) for WWW
http://icsd.ill.fr/icsd/
The free part of the excellent database is small
(3,325 out of 76,480 in 2004), still it may be useful.

(From MMikami 041027)
"Teaching Pamphlets" for Crystallography 
http://www.iucr.org/iucr-top/comm/cteach/pamphlets.html
are available at the IUCr site (http://www.iucr.org/).  

You might also be interested in some hyperlinks there:
- about CIF (Crystallographic Information File):
  http://www.iucr.org/iucr-top/cif/index.html
- SINCRYS (Information Server for Crystallography)
  http://www.iucr.org/sincris-top/

The mincryst crystallographic database, with 6000 minerals :
http://database.iem.ac.ru/mincryst
