Is Wine even useful for anything other than proprietary software?

I suspect that most people use it for that but surely there must be free software programs available for Windows too?

Although, if there were a free program for Windows and I liked it, I'd rather port it to run on GNU/Linux instead...

I used it to write this documentation

I used to use Wine to run Notepad++, a free Windows-only text editor, before I started using Emacs. So yeah, I don't think there are very many Windows-only free programs, but there are a few.

The OSSWin project has a number of free software Windoze projects.

As these are "Open Source" programs, please be aware that they may not meet the standards of Free Software. Most seem to, though. Please drink responsibly.

https://www.gnu.org/philosophy/open-source-misses-the-point.html

One additional caveat: I don't know how up-to-date any of them are, but here you go...

http://osswin.sourceforge.net/

There is free software that runs on Wine and does not have a native GNU/Linux version. Take a look at this list of free software.

Thanks for the responses guys. :)

Wine is being used in ReactOS, a free replacement for Windows. Apparently ReactOS might ship with some non-free software though, which is a shame.

Anyway, to me I consider Wine to be similar to Gnash. Gnash is primarily used for running non-free ActionScript, but at least that's better than relying on a non-free runtime environment.

(I don't use Gnash for this reason, but I support their project!)

Of course there is some free software, like Notepad++, that's only available for Windows which can be run with Wine.

Yep! There are plenty of Windows-only free software projects: http://en.wikipedia.org/wiki/Category:Windows-only_free_software

Of course, many of these have alternatives in GNU/Linux that work well too, or could be ported.

There are some "free software" graphics editors and similar applications which are dependent on non-free Microsoft Windows components. These components are non-free programs written by Microsoft, bundled in MS Windows, and relied upon by these "free" programs. Many of these developers will not port these applications to GNU/Linux because it isn't easy to do.

If these projects were written in a more cross-platform oriented manor this would not be difficult. WINE is handy to port these "free" programs to GNU/Linux because WINE is a re-implementation of these non-free Microsoft dependencies.

There is nothing wrong with WINE. The problem is its used mostly to run programs that aren't even mostly or partially free.