Solution Instance Visualizer is an Visual Studio extension to visually separate instances of visual studio, making it easier to quickly identify which project or branch is currently at hand. Implemented as a tool window without any proper functionality apart from showing customizable colours and text.
To start using it, go to View -> Other Windows-> Instance Visualizer. Then - once a solution is opened - click the icon in the upper right corner to adjust settings (colour & text).
The settings are stored in an xml file (per solution), so the settings may be shared with other team members.