<p>Is there a better <strong>free</strong> TreeView control that exists for Visual Studio 2008 / .NET 3.5?</p>

<p>I believe I need something a little more powerful than the out-of-the box version. I'm not exactly sure for what yet but I thought I'd ask quickly before I get too far in to my project.</p>

TreeViewAdv
seems to be pretty nice. It is described with the following features on SourceForge.net:
Extensible advanced TreeView.
100% management C# code.
Features: Model/View architecture.
Multicolumns.
Multiselection.
Different controls for each node: CheckBox, Icon, Label ...
Drag&Drop highlighting.
Load on demand.
Incremental search.
We will most likely use this in one or two occasions in an upcoming project, IIRC.
HTH