I've been meaning to publish this for ages, so after nearly a year of planning......

Software

Resharper : Simply the best .NET tool... FACT. Try it once and you'll never go back.
Son Of Obsidian : Cool Visual Studio theme that will help reduce eye strain
Stylecop : Provides a very simple way to introduce coding standards to your work.  VS will point out all your small discretions so you don't have to worry about them anymore.
FX Cop Intergrator FX Cop Indigo Studio Brilliant and simple wireframing tool.
Diffmerge SQL Complete Intellisense for SQL!
Keypass Best password manager I've used.
Fiddler Useful for debugging in IE and doing network troubleshooting
Manic Time Tracks your time easily
M-remote Great RDP client. I haven't used remote desktop in years.
dotPeek Brilliant free replacement for reflector.
Isapi Rewrite Redirect module for IIS, getting more obsolete nowadays
SQL Profiler Free SQL profile when you only have SQL Express on your server 
Sublime 2My Favourite text editor
Dia Really handy if you need to knock up a quick ERD diagram
Launchy Lightning fast program launcher from your keyboard
Dropbox File back-up
Xenu Can be a life saver if you get 500's on your web server. Finds all broken URLs on your site.
Unlocker Unlocks files that have been locked by Windows, essential tool!
SourceTree  Git client for Windows
Virtualbox Essential for cross browser testing
ClamWin AntivirusFree anti-virus

Cool Frameworks and software

Trello By far the easiest and simplest project management tool I've ever used.
Harvest Cool time tracking software, integrates with Trello
Wordpress Great for knocking a site up quickly.
N-Unit Great unit testing framework
Fluent Assertions Write Unit Test easier
GSA Lib Brilliant wrapper for Google Site Search
Infragistics Great component library for desktop and web apps
Snippet Compiler
StructureMap Nice DI framework
Automapper, Simplify object mappings Bootstrap Makes your site look a million times better in seconds