There are many applications available that run on Mono. Some use Gtk#, some use Winforms, and some use something entirely different. Here are a few examples.

To see Moonlight in action, please see Moonlight Shots.

Gtk# Applications

Banshee (http://banshee-project.org/Main_Page) Banshee is a music organizational and playback tool.
Beagle (http://beagle-project.org/Main_Page) Beagle is a search tool that ransacks your personal information space to find whatever you're looking for.
F-Spot (http://f-spot.org/Main_Page) F-Spot is a photo management application for the GNOME desktop.
MonoDevelop (http://www.monodevelop.com/Main_Page) MonoDevelop is a free GNOME IDE primarily designed for C# and other .NET languages.
MonoUML (http://www.monouml.org/) MonoUML is a CASE tool designed for allowing all UNIX/Linux developers faster computer systems design using a friendly GUI application. Muine (http://muine-player.org/wiki/Main_Page) Muine is a graphical music player with a simple, intuitive interface.	MonoUML	Muine
OpenVPN-Admin (http://sourceforge.net/projects/openvpn-admin) OpenVPN-Admin is a GUI for OpenVPN that runs under Linux and Windows. SkyNET (http://sky-net.sourceforge.net/) SkyNET is written in C# and uses Gtk# for displaying a star chart.	[url=http://www.mono-project.com/Imagepenvpn-admin.png][/url] [url=http://www.mono-project.com/Imagepenvpn-admin.png][/url] OpenVPN-Admin	SkyNET
Tomboy (http://www.gnome.org/projects/tomboy/) Tomboy is a desktop note-taking application for Linux and Unix. Simple and easy to use, but with potential to help you organize the ideas and information you deal with every day.	[url=http://www.mono-project.com/Imageomboy1.png][/url] [url=http://www.mono-project.com/Imageomboy1.png][/url]	[url=http://www.mono-project.com/Imageomboy2.png][/url] [url=http://www.mono-project.com/Imageomboy2.png][/url]

Winforms Applications

SharpChess (http://sharpchess.com/) SharpChess is a free computer application that enables you to play chess against the computer. Reversi (http://www.codeproject.com/csharp/Reversi.asp) Reversi is a popular game that is fun, requires just a few basic elements and has simple rules.	SharpChess	Reversi
MonoCalendar (http://www.monocalendar.com/) MonoCalendar is an application designed for easy management of calendars.
NUnit (http://www.nunit.org/) NUnit is a unit testing framework that is open source written in C#.
MoMA (http://www.mono-project.com/MoMA) MoMA is a tool that helps you identify issues you may have when porting your .Net application to Mono.	[url=http://www.mono-project.com/Imageinmoma1.png][/url] [url=http://www.mono-project.com/Imageinmoma1.png][/url]	[url=http://www.mono-project.com/Imageinmoma2.png][/url] [url=http://www.mono-project.com/Imageinmoma2.png][/url]

Other Mono Applications

Eclipse (http://www.eclipse.org/) Eclipse is an IDE written in Java. It can run on Mono using IKVM (http://www.ikvm.net/), the Java VM for .Net.
Maemo (http://www.mono-project.com/Maemo) Mono can be run on embedded devices like the Nokia 770. A video of the Nokia 770 running Gtk# is available here (http://www.go-mono.com/nokia/nokia-gtksharp.mov).