What is a list of third party tools available to support SharePoint 2010 developers?
One answer per tool please so the community can vote.
This question has been up several times before
For SP2007, which still applies for most tools
The most important 3rd party tool is without doubt Community Kit for SharePoint CKS:DEV that extends the Visual Studio Studio integrated tools for SharePoint development.
The Imtech Create Page Layout Extenstion (SP2010) can be put to good use also: http://visualstudiogallery.msdn.microsoft.com/en-us/990bd0c8-a55b-4643-a35d-88136594c3d9
Off-course, most of the Imtech solutions are very good for Sharepoint development.