A simple list of items no developer should be without.

VS 2010 Productivity Tools
http://visualstudiogallery.msdn.microsoft.com/en-us/d0d33361-18e2-46c0-8ff2-4adea1e34fef

OData Visualizer
http://visualstudiogallery.msdn.microsoft.com/en-us/f4ac856a-796e-4d78-9a3d-0120d8137722

VS2010 Code Map
http://visualstudiogallery.msdn.microsoft.com/en-us/1c54d1bd-d898-4705-903f-fa4a319b50f2

RegEx Editor
http://visualstudiogallery.msdn.microsoft.com/en-us/55c24bf1-2636-4f94-831d-28db8505ce00

TFS Power Tools
http://visualstudiogallery.msdn.microsoft.com/en-us/3e8c9b68-6e39-4577-b9b7-78489b5cb1da

Power Commands for VS2010
http://visualstudiogallery.msdn.microsoft.com/en-us/e5f41ad9-4edc-4912-bca3-91147db95b99

Visualization and Modeling Feature Pack
http://msdn.microsoft.com/library/dd460723.aspx

Application Architecture Guide Layer Diagrams
http://visualstudiogallery.msdn.microsoft.com/en-us/237f823c-45b4-4f1f-b9e2-607fe66eaae7

Architecture Layer Patterns
http://visualstudiogallery.msdn.microsoft.com/en-us/9c8051f8-e8f7-45b1-8d04-dad6afc697d2

Move to Region
http://visualstudiogallery.msdn.microsoft.com/en-us/993418d7-40ef-46fd-8f2d-0cf57cc628fd

ReSharper
http://visualstudiogallery.msdn.microsoft.com/en-us/EA4AC039-1B5C-4D11-804E-9BEDE2E63ECF

PowerGUI
http://www.powergui.org
http://powerguivsx.codeplex.com/

WIX
http://visualstudiogallery.msdn.microsoft.com/en-us/5f43f268-7752-48c7-90e8-ae5b6f136b3f

Code Contracts Editor
http://visualstudiogallery.msdn.microsoft.com/en-us/85f0aa38-a8a8-4811-8b86-e7f0b8d8c71b?SRC=Featured