I recently had a complete melt down of my work laptop which required our IIS team to repave the entire thing. I decided to keep a track of the most important things I need to add to a new baseline machine (not including Office).

• Beyond Compare - Beyond Compare allows you to quickly and easily compare your files and folders.
• UltraMon - UltraMon is a utility for multi-monitor systems, designed to increase productivity and unlock the full potential of multiple monitors.
• Password Agent - An easy-to-navigate password management program that allows you to store all your passwords, secret notes and data snippets in a single, secure database.
• Notepad2 - A fast and light-weight Notepad-like text editor with syntax highlighting. This program can be run out of the box without installation, and does not touch your system's registry.
• Magic ISO - MagicISO is a powerful CD/DVD image file creating/editing/extracting tool. It can open / create / edit /extract CD/DVD image files, and it can convert bin to iso and back.
• Visual Studio 200X – ‘nough said
• NAnt - NAnt is a free .NET build tool. In theory it is kind of like make without make's wrinkles. In practice it's a lot like Ant.
• Windows Powershell - A new command-line shell and scripting language designed for system administration and automation.
• Reflector - Explore and analyze compiled .NET assemblies, viewing them in C#, Visual Basic, and IL.
• SysInternals - Sysinternals utilities help you manage, troubleshoot and diagnose your Windows systems and applications.