Is there an XAD port for Windows? The SourceForge page has very little information on the project (but more than anywhere else I can find on the net) and seems to indicate it doesn't work for Windows:
[quote="SourceForge"]Shared library for archive and file unarchiving and extraction. Based on the Amiga system of same name.
Project Admins: stoecker
Operating System: All POSIX (Linux/BSD/UNIX-like OSes), AmigaOS, MorphOS
License: GNU General Public License (GPL), GNU Library or Lesser General Public License (LGPL), Public Domain
Category: Compression, Packaging[/quote]
A few days ago I had a quick look at what would be involved in writing a 7Zip plugin (looks pretty doable since there's a convenient API), and a read-write RAR plugin (looks like a pain in the arse because there's no API or library for creating RAR files so you'd have to do it by runnign WinRAR.exe on the command-line, but still use UnRar.dll (which is slow/crap for random access, though that could be improved) for listing the contents of archives because WinRAR.exe has no list command and rar.exe cannot list unicode filenames... Argh.).
Other formats like LHA and TAR etc. would be nice but, even with 7Zip (which is nice but not used by many people), it feels like a lot of effort for each format.
If there was a single library which could be used to add support for all formats then that would be awesome and would make the effort seem worthwhile.
As it is, most people who want more than Zip and read-only RAR seem to want read-write RAR support (god knows why; I wish RAR would die if it's never going to be licenced or converted into an API/library) with a few people also wanting 7Zip (which I can understand, it's a nice compression format).
Several people have talked about writing archive VFS plugins but so far nobody has. 
I'm trying not to add myself to that group since, although I've started looking into it, I don't know if I'll write one myself, or if I'll continue working on my graphics-based plugins, which I don't consider finished yet. We'll see. I expect it'll turn out that two of us write one at once. 
If anyone is actively developing such a thing then please speak up.
Another thing I've been considering is a semi-generic "command-line archiver" VFS that wraps the command-line versions of tools into something Opus can use. It'd need a bit of work for each tool, to understand how it lists files and its command-line syntax, but it might mean less effort is required for each file format, so obscure stuff that nobody should be using in this day and age could still be supported to keep everyone happy. Unfortunately there are drawbacks with this approach: RAR listing can't be supported with it (though extraction and addition can be) and I expect several other formats have issues with Unicode filenames on their command-lines. It also involves parsing text output from programs, which I think sucks (but is better than nothing).
(I'm still entirely happy with Zip myself. I can't remember the last time I cared about the exact size of a file, how long it would take to transfer it, splitting an archive into parts or any of that 1980s stuff. But that doesn't mean I won't write a plugin. I've got no use whatsoever for the RAW camera plugin but I still made that for other people. )
