ContainerGameComponent is a class derived from DrawableGameComponent and has a Components property, similar to XNA Game class. It can be useful to group your GameComponents in different manner or to build complex hierarchies of GameComponents.

The Game Development Framework (GameFX) is simply a set of libraries to be used as the foundation for any simple 2D tile-based game. It can be used to build games such as PacMan, Snake, Tetris, and even Chess. GameFX will handle tile-based maps, graphics, and pathfinding AI.

GDIdotNETgames is a basis for "user-moddable" 2D strategy games using GDI+ graphics with .NET managed code written entirely in C#.

X-Forms is a Graphical User Interface Framework to aid in the creation of User Interfaces within Games created using the Microsoft XNA Framework. X-Forms is built to reflect how .NET Windows Forms work. It provides support for full screen Forms and Controls. The project aims to help with rapid GUI development and currently works on Windows PC and Windows Phone 7.0

XNACC is a component that adds an interactive command console to your XNA project. It supports many built-in commands, as well as custom commands...

Toolkit of Components, Services, Wrappers, and Utilities for use in your XNA game. Currently provides a Stationary and First Person Camera component, Input service and component, Audio wrapper, and EventLogger (Windows Only). Weapon inventory, menu system, and performance tracking components will be added to the library soon.