I’ve seen blogs like this in the past, so I figured I’d throw together my list:

4NT – a great replacement for cmd.exe
ActiveState Perl
ViM – a great text editor
HyperSnap-DX – a great screen capture program
DocClear – my own program for managing the entries in the ‘Documents’ menu
WinZip
SharpReader
Gravity
Trillian
Lavasoft Ad-aware

I spend a large portion of my day at the command-line (4NT), using ViM.