ScintillaNET - a .NET enabled version of the Scintilla Editor Component (see http://Scintilla.org) This project is now hosted at CodePlex (http://www.codeplex.com/Wiki/View.aspx?ProjectName=ScintillaNET) or (http://www.scide.net)
NESide is an IDE specially made for coding in assembly language for the NES. Featuring syntax-coloring and integrated editors for palette and name tables.
Also includes a plug-in system for extensibility.
Powerful example of a FULLY pluggable multimedia and text editing and review suite - support for an extensive range of file types can be provided for by the use of plugins, and properly-formatted XML modules.
Sphere Suite is an IDE for the RPG Creation Engine Sphere, with an excellent interface and plenty of code helping tools. With a highly customizable interfaces and great coding utilities and a built-in script for Sphere Suite is the best choice for an IDE