Four of my favorite utilities:

• Text Pad - great text editor (bettern than notepad or wordpad)
• .Net Command Prompt Here - great short cut for running command line stuff
• Beyond Compare - my new favorite way to update sites (file and folder comparison utility). If you move files from development to QA or prod or whatever -> check this utility out!
• Lutz Roeder's Reflector - great tool to view source code of compiled .net assemblies, make sure you add it to your Send To directory

Scott has a REALLY good list of Tools too. I don't see Beyond Compare on his list though.