In order of use:
Internet Explorer
Lotus Notes (I constantly use it at work)
Lotus Sametime (It's pretty much an encrypted version of AIM)
Outlook Express (I use that for mail at home)
WS-FTP
Microsoft Office
Lotus SmartSuite (Wow, and boy does it suck!)
telnet (gotta remote control my UNIX boxes!)
VNC (gotta remote control my NT boxes, too!)
Netscape (Only for those sites that IE chokes on)
I also use Microsoft Money, Adobe Acrobat, Bearshare, WinZip, and Sim games a lot too.