Jetbrains Resharper is an extention that you can add to Visual Studio. The tool assists the developer to create code and to refactor existing code. It performs static code analysis while you create code as well as allowing the developer to safely rename and refactor existing code. This tool is the best way to get the programmers to code in a consistent style (through suggestions and refactoring) and it also good for reviewing code. For instance a function that returns early and make the rest of the code redundant will be highlighted to the developer. There are many hotkeys for navigating and refactoring with the tool. The most used key combinations are ALT + ENTER to open the suggestions and ALT + PageUp\PageDown for Next\Previous issue.
LINQPad has a free and a licenced version. It supports writing code snippets and testing functions. The application supports C#, F# and VB. Before when you wanted to test a function or code you would create a console application in visual studio. This would allow you to try something without having to write a user interface. With LINQPad you can create a function or statements and run the code using its built in console.
Codemaid is a Visual Studio extension that allows the developer to perform code cleaning, reorganising and formatting really fast with the commands. The tool also gives a treeview where the developer can see the structure of the code mapped out. It is a really effective tool to visualise the classes and methods
XMind is not a developer tool but a mind mapping tool. You can create individual brainstorming maps or collaborate as a team. I really like the ability to drill down into diagrams and link diagrams and sub diagrams together. It is the first tool that I use when creating requirements or technical documents. I am able to capture my thoughts and also log thoughts to revisit whilst focusing on each option. It has ways to export the maps to Office, Images, PDF's etc.