For those of you who are working with Open XML files, there is a great tool out there on Codeplex called the "Package Explorer". It's an open source project that's already pretty far along, and it was started by Wouter Van Vugt. Wouter is one of the more well known voices in the Open XML community, and this tool is perfect for those folks looking to operate directly on the XML within an Open XML document. Here is a video where Doug Mahugh and Wouter talk about the project: http://channel9.msdn.com/ShowPost.aspx?PostID=292735

I'm currently using version 2.1.3.0 and it really does make it much easier to work with the files. You can navigate through the packages via relationships, and quickly dive into any one XML part to make edits. Here's a screenshot:

It makes it really easy to make quick changes to the XML, and then see what that looks like when you reopen the file in an application that supports Open XML. Each part has the name, but you can also specify to display the relationship id that was used to reference the part. So in the example above where I'm navigating through a PresentationML file, I can go from the "presentation" part that defines the order of the slides, and quickly see that the first slide has the "rId2" relationship ID. Then you can look over at the explorer and find the part that is referenced with the "rId2" ID. Hopefully Wouter will eventually add hyperlinks to the relationship references so you can just click on them to navigate to the next part…

-Brian