Compression

7-Zip
Universal Extractor
Hoazip

Download Sites

FileHippo: Like Download.com, without the garbage (and provides legacy versions).

Images / Pictures

Picasa
Paint.Net
(that tiny Photoshop like tool?)
Gimp 

Firewall

Comodo
PCTools
DefenseWall (Paid)

Sandboxing

Sandboxie
    BSA (for Sandboxie)

Registry

ERUNT

Malware / Spyware Removal

SuperAntiSpyware
Malwarebytes

Password Manager

KeePass
LastPass 

Extract Windows security certificates

Jailbreak from iSEC Partners: 

https://www.isecpartners.com/jailbreak.html

Anti-virus

Microsoft Security Essentials
AVG Anti-Virus
Panda CloudAV