Are other IDEs available for .NET development besides Visual Studio?

Sharp Develop is an open source, cross platform IDE for .NET languages, available at
http://www.icsharpcode.net/opensource/sd/

Eclipse is an open source, cross-platform IDE for Java and other languages, available at
http://eclipse.org

A plug in for C# development with Eclipse is called Emonic, available at
http://emonic.sourceforge.net/