Ruby programmers using Windows should definitely give this a look; this is very high on my "IDEs to look out for" list. It should be noted that this is not a CLR / .NET-based Ruby; it's a plug-in to Visual Studio (Standard Edition and above; unfortunately, VS Express users are out of luck) that targets the standard Ruby interpreter.

Although Scite has it's charms (like loading in a fraction of a second), VS is definitely a superior environment for extended development.