Freeware .NET split-button (dropdown button) control for .NET WinForms. Supports all versions of .NET framework and all Visual Studio versions.

It has native look and feel so it supports all Windows themes, including modern ones. It is highly customizable (images support, imagelist support, adjusting the split-part, etc).

Supports regular ContextMenuStrips for the dropdown menu. Can be set to AlwaysDropDown.

Written in pure managed C# code, tiny single DLL file that is simple to deploy using XCopy.

Includes samples both in VB.net and C# as well as samples explorer.

Better SplitButton is free for non-commercial use and comes with a cheap source code licenses for commercial use.