Usefull links
1. Chemistry and Crystallography
Inorganic crystal structure database (ICSD). Link 1 (require subscription), Link 2
Other databases: NIMS - AtomWork, Mineral database, Cod
Simplest thermodynamic phase diagrams: OQMD
2. Physics
Table of Shannon's ionic radii
MAGNDATA: Database of various magnetic structure
List of the 1st ionization potentials
List of the Metal-metal bonds
3. Symmetry (mostly Bilbao Crystallographic Server)
Convert CIF/POSCAR
Visualization of space and point groups (and their elements)
Magnetic point groups
Wyckoff positions for all space groups (see also International Tables)
Find symmetry tool
5. Math
Matrix operations on-line: Brunner's tools, BlueBit (column corresponds to each eigenvalue)
Point group characters
6. Travels
Cheap tickets search: yandex, skyscanner.ru, hipmunk.com, kayak.com, anydayanyway.com
Map of cheap flights: map.aviasales.ru
Map of current flights: flightradar24.com
Flight statistics (delay etc.): flightstats.com
Prices in different countries: numbero.com
Power sockets and plugs in different countries: world-power-plugs.com
Time Zone Converter timeanddate.com
7. Other
Check english pronunciation forvo.com
Important formula
jeff=1/2 and jeff=3/2