Visual Studio Team System isn't really an addon, but it adds a lot of great functionality to Visual Studio Professional. The most important features I use is source control, the testing framework, build system and code analysis, and the main benefit is that everything is integrated in Team Foundation Server. I haven't spent much time with Team System 2008, but I'm attending Brian Randell's pre-conference at PDC08 tomorrow and I expect I'll have a deeper understanding of the product tomorrow. I also hope to see more of Team System 2010 at PDC in the coming days, but until then Channel 9 has a lot of great videos of some of the new features.
- JetBrains ReSharper
- JetBrains dotTrace Profiler
- Consolas True Type font
- Innovasys DocumentX!: WYSIWYG editor of code documentation inside Visual Studio, and a help file compiler.
- Guidance Automation Extensions and various software factories from Microsoft Patterns and Practices
- Web Services Enhancements 3.0 for creating secure web services in VS2005. WSE doesn't support VS2008, but Jason Young has a solution that I want to try out soon.
- Axialis IconWorkshop Lite: I haven't used this much, but it is a great free addin when you're working with icons inside Visual Studio.
- StyleCop. Like Code Analysis/FxCop, but checks the formatting of your code.
Keyboard shortcuts (with Visual Studio keyboard mappings in ReSharper)
- Alt+Enter: Drop down ReSharper's smart tag
- Ctrl+.: Drop down Visual Studio's smart tag
- Ctrl+Alt+Space: ReSharper's smart completion
- Ctrl+Shirt+Enter: ReSharper's complete statement function
- Ctrl+Shift+F: Find in Files
- .NET Reflector and ildasm: Tools for inspecting assemblies.
- WiX: Powerful framework for generating setup files.
- fuslogvw: Great tool for debugging assembly load errors.
- Visual Studio Theme Generator. I ended up with just a slight modification of the standard Visual Studio Theme, but this tool allows you to quickly generate color schemes that matches your preferred primary colors.
- Sandcastle: An alternative to DocumentX! that I use when generating help files whit long file paths due to long and nested namespaces.
I probably have forgotten a thing or two, because I've recently reinstalled my laptop and from my hotel room in Los Angeles I don't have access to my file server where I keep a copy of every thing I add on to Visual Studio.