I'll second some previous nominations along with others:

My Can't live without tools:

- Beyond Compare

- KeePass

- Launchy

- ScitTE

- AutoHotKey

My other standbys:

- IrfanView

- Notepad2 (for portable editing on other machines)

- 7zip

- Foxit PDF Reader

- Agent Ransack

- Filezilla

- Sysinternals Suite

- SQL Compare/SQL Packager

- SQL Complete Express Edition

And then there is the glue to make everything work .. scripts.

I am absolutely dependent on my scripts. They are mostly self-developed, in a variety of scripting languages as suitable for the task at hand; batch file, PowerShell, Perl, VBScript