The ArcGIS Snippet Editor is a new feature of the ArcGIS integrated development environment (IDE) that comes with the ArcGIS Desktop and ArcGIS Engine software development kit (SDK) for 9.3.1.
The snippet editor allows you to create, edit and manage ArcGIS snippets in Visual Studio 2005 or 2008. It supports both VB.NET and C# code snippets.

Be sure to check out this video as it illustrates how to accomplish the following:
Snippet Editor Manager
Create a snippet (Function, Sub or Statement)
Auto-reference ArcGIS assemblies
Set the product, version and extension
Set title, description and help string
Store in a custom file path location
Snippet Finder
Search and find snippets by key word
Insert snippets into code windows
You'll also find other helpful tips and tricks such as how to set the default snippet editor directory in Visual Studio for a system with Windows Vista.

Contributions from Don Kemlage, ArcGIS Product Engineer