Is there an Expression Tree Visualizer for VS 2012?

What you can do is fix the visualizer for vs 2010 so it works in 2012. This is very easy. Just get the source from this project : http://exprtreevisualizer.codeplex.com/ and change the DebuggerVisualizers assembly reference of the ExpressionTreeViewer project to :

C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\IDE\ReferenceAssemblies\v2.0\Microsoft.VisualStudio.DebuggerVisualizers.dll

So that it works with the newest version of vs2012. After that copy the results to

C:\Program Files (x86)\Microsoft Visual Studio 11.0\Common7\Packages\Debugger\Visualizers

and it should work