I had to make my own editor, since nothing that I found worked under Windows 7.
I thought that someone else might like to use it. It can be installed from
http://stash.miloonline.net/Apps/TVZip/.
Quick how-to (I'll type up something more comprehensive if there's enough interest):
Create or modify the contents of a package simply by dragging files into the package window (which is just above the mesh preview frame).
Open a package by browsing to it in the left-hand pane, or by entering its path into the path bar, or by dragging the file into the path bar.
Create a new folder inside the package by clicking the folder button.
Reload a package file by clicking the reload button.
Save a package by clicking the floppy disc button.
Rename a packaged asset by selecting it then pressing [F2].
Delete a packaged asset by selecting it then pressing [Delete] or the "X" button.
Packaged assets may be dragged and dropped within the package file. Contents are auto-sorted, first by type then by filename.
Preview a packaged asset by double-clicking it, or selecting it and pressing [Enter] (currently only meshes, actors, and particle systems).
Paths to folders or package files can be bookmarked using the green bookmark icon.
Extensions recognized as TV package extensions are .tvpack, .tvpak, .tvpkg, .tvpk, .tvzip, and .tvz.
Note that this is first revision, of course; I've tested it with my own projects, and it's working well, but there are some features that I won't be adding until later this week (e.g. previewing images and text files).
