Just found this: http://www.codeproject.com/KB/audio-video/dsgraphedit.aspx
DSGraphEdit is a library to easily add functionality similar to Microsoft's venerable GraphEdit to
your .NET applications. Most of the functionality has been recreated
with a few new bells and whistles to aid in the debugging of DirectShow software.
There's a demo app that wraps the library in something executable. It's pretty, to say the least, giving you the filter properties and rendering right there on the graph blocks.