Opera:

Opera is a tabbed browser that is almost completely customizeable. Once I started using it I fell in love. One of the nicest features is Hand gestures, which I find myself trying to do on all sorts machines, even just in windows.
Without a doubt, this is my top browser. I *highly* recommend it for you ADDers out there. It keeps track of EVERYTHING.
http://www.opera.com

Trillian:
Meh, I know keeping track of 3 IM programs and a chat client was more than enough for me, so I tried Trillian as a chat client and I'm loving it.
It handles
Yahoo
AIM
MSN
ICQ
and
MIRC

Google desktop:
If you're anything like me you get lost trying to sift through the files on your computer. I find myself backtracking constantly trying to find programs et cetera. Google desktop indexes all of the files on your computer and allows you to search them, just as you would in google.

If you want to find the last two just use google to locate them, I can't remember the links =(

I use morpheus and mozilla for browsers.

Ewido online spyware scan
Adaware SE spyware scanner
AVG virus
Zonealarm firewall
Sygate firewall is also an option
Everest computer analyzer and memory checker