FYI, we have just released the NuGet Package Explorer tool. (http://nuget.codeplex.com/releases/view/59864)
This is a little tool that helps you, especially package authors, quickly view the metadata and content files of a .nupkg file. It is released as a ClickOnce application. After you install it from the link above, it will auto-register the .nupkg extension
with the tool (provided that you have not already associated the extension with another program) and from then on you can just double click on a package file to view its contents. Please try it out and post your feedbacks here. As always, we
welcome feature suggestions and bug reports.
Known issue: We are not able to authenticode sign the tool right now. So it will appear as an untrusted publisher on the ClickOnce install window. We're working on signing it.
Tip: Inside the file contents tree, you can right click on a file to choose to view its content (text files only) or save it to disk. I know it's not very obvious from the UI :)