'Spam Screener', and 'Winpooch'

Spam Screener

State-of-the-art challenge - response spam blocker. Set it up and enjoy no spam in just one minute! Challenge - Response (or permission-based) spam blocking is a technology that requires email senders to get your approval before they can email you, similar to how someone knocks on your front door before entering your home. To be more convenient, SpamScreener Free Edition will automatically synchronize with your address book so that your existing correspondents are already approved to send you mail (Outlook/Outlook Express/Eudora). And SpamScreener Free Edition will protect you from opening spam viruses and worms, too.

http://www.georgesoft.com/spamscreenerfree/

Winpooch

Winpooch is a Windows watchdog, free and open source. Anti spyware and anti trojan, it gives full protection against local or external attacks by scanning the activity of programs in real time. Winpooch uses the API Hooking method. It spies programs when they are running and gives the user control. For example, you can forbide a program to write in a system directory or in the registry, or else to connect to internet. That makes it different from other anti spyware using a database of known signatures.

http://winpooch.free.fr/home/index.php