PortableApps.com

Ever wanted to carry around your favourite applications without dragging your computer. I have, this is why the suite of products and interface offered by portableapps.com are so excellent, because you can install them to USB memory stick and plug'n'play anywhere.

Requirements:
Microsoft Windows XP, or higher

Download from:
http://portableapps.com/

Screenshots:

Spamihilator

Tiny little program that sits in your system tray filtering your email for spam. It's free and it really does work. The product also allows for third-party plugins, which improve functionality, not that it needs it. An excellent spam warrior!

Requirements:
Microsoft Windows XP

Download from:
http://www.spamihilator.com

Screenshots: