Software:

OmniCon98 - physical units conversion utility (shareware)
Convert - conversion of different code pages (freeware)
Chemical Engineering Tools - on-line
Uklad okresowy pierwiastków (freeware)
Inoculate Personal Edition (FREE) - antivirus
Ghostscript, Ghostview and GSview - to view/produce/print postscript files

Knowledge bases:

Materials Science
Electronic and physical properties of semiconductors
Tablice Fizyczne
Stałe fizyczne
Układ okresowy pierwiastków

Interesting links:

SensorTech
PUNCH - Computational Electronics
SensorScan
The Semiconductor Subway (MIT)
Sensors WordLink

The Semiconductor Applet Service - a lot of useful Java applets