Open Science Project offers freeware for chemical and physical analysis. Take a look
CCP14 is website hosting free computional software for the physical sciences.
WinZip software for opening and building compressed files
WinRAR another program for building and opening compressed files
GSView is a graphical interface for viewing and building postsript (.ps) documents
Ghostgum is software for viewing both postscript (.ps) and Adobe pdf files
WinSCP is a secure ftp or ssh program
PHREEQC is a program used in geochemistry and inorganic chemistry
MiKTeX is Latex or Tex program for Windows operating systems. Tex is a typesetting program
WinEdt is an ASCII editor and shell for Windows operating systems
ChemSketch a free organic and inorganic chemistry sketching program
Invitrogen a software company for Bioinformatics and other Biochemical and Biomedical analysis. The software is free for educational and public research purposes
PuTTY a free SSH and Telnet client. Plink a UNIX operating system connection client is also found at the same location
OpenOffice.org is a free Office Suite similar to Microsoft Office Suite and is avaible for most operating systems.