This is a simple framework written for Monogame for those who don't want to code their own UI. Features: Buttons, Check Boxes, Menu Bars, Labels, List Boxes, Progress Bars, Sliders, Text Boxes, Windows, UI Separation
You can simply include the UIFramework.dll as a reference to any Monogame project and it should just work. Don't forget to include the UIFramework namespace into any file using the framework.
This was coded a long time ago and isn't updated regularly since I no longer use MonoGame, so I can't guarantee that it still works flawlessly.