LINQPad - A scratchpad for C#, F# and VB code including Linq queries.
Quiver - Quiver is a notebook built for programmers.
Linqer - Linqer is a SQL to LINQ converter tool.
Snippely - Snippely is a basic text and code organizational tool.
Dot Net Editor - An VB/C# text editor with the ability to run code and code snippets.
GitHub Gist - Gist is a simple way to share snippets and pastes with others.