Windows Open Source Utilities

See also The table of equivalents / replacements / analogs of Windows software in Linux.

SDelete

To zero out free space use SDelete http://www.microsoft.com/technet/sysinternals/Security/SDelete.mspx from Microsoft Technet. 

Example:
sdelete -c c:temp

Putty

Use Xming portable PuTTY to give you a tight X Window Server as well.
Go here for the original PuTTY. 

Xming - X Window Server
JWhich

JWhich is a program to find Java resources such as class files or property files. Just as the Unix which command finds executable files by searching the PATH, JWhich finds Java classes by searching the CLASSPATH.

Monitoring Tools

Nagios: http://www.nagios.org/
Zenoss: http://www.zenoss.com/

Perforce
A simple Backup Script:

$ cat bin/backup.sh
#!/usr/bin/sh

cd /cygdrive/c/projects
rm -f /cygdrive/c/projects/*.zip
for d in `ls -1`; do jar cfM $d.zip $d; done

cd /cygdrive/C/tu/Documentation
# rm -f DocumentationBuild.zip
jar cfM /cygdrive/c/projects/DocumentationBuild.zip Build

# rm -f SolutionDesign.zip
jar cfM /cygdrive/c/projects/SolutionDesign.zip SolutionDesign
# mv -f /cygdrive/c/tu/Documentation/*.zip /cygdrive/c/projects

mv -f /cygdrive/c/projects/*.zip /cygdrive/f/

WinMerge

An Open Source file merge utility.

Open Source Firewall Software for Windows

SensiveGuard is license free for personal use.

http://www.sensiveguard.com/download.html

iSafer - a Winsock firewall.

http://isafer.sourceforge.net/

iSafer Sourceforge site:

http://sourceforge.net/project/showfiles.php?group_id=118375

Tail for Win32

Tail for Win32 is a Windows version of the UNIX 'tail -f' command.