We also have this need! We want to embed an easy markup toolbar into a .NET application so the reviewers of a plat/cad file can just mark it up right there in the .net pages, not have to have the client installed and have to publish and upload it back to our .net pages. It would be super cool. We are currently doing this with a BRAVA integration in Lotus Notes, but it's old and needs replacing, thus the .NET solution and free Autodesk Design Review. If we could integrate the markup with the .NET that would be perfect.