I spend most of my dev time in Visual Studio. I hate to go out of VS and open some other programs like fiddler or reflector. In Visual studio you can easily add the tools that you use a lot by adding these tools as external tools.
All you have to do is go to Tools->External Tools, configure your tool over there ... Heres a screen shot of to configure Reflector in Visual Studio..
Thats it.... next time you want to use the reflector... all you have to do is go to tools and select Reflector.