Yes, SoC is usually about coding new stuff rather than writing conformance tests, but here's a situation where we badly need more conformance tests *and* the tests are a real challenge to write.
Rob Sherman, who is one of the OLE code maintainers, remarked recently that we could really use more test cases for part of COM/OLE: http://www.winehq.org/pipermail/wine-devel/2006-May/047401.html
Many apps have OLE problems; the query http://bugs.winehq.org/buglist.cgi?long_desc_type=substring&long_desc=er... finds 109 hits. Maybe a third of these are really OLE problems that could be repeated by conformance tests. (I think http://bugs.winehq.org/show_bug.cgi?id=4073 http://bugs.winehq.org/show_bug.cgi?id=4776 are good examples.)
Writing COM or OLE Automation tests in C is hard - the documentation you need is in old books that are hard to find. But it's doable given a couple weeks.
There are a few links to writing COM in C at: http://www.winehq.org/pipermail/wine-devel/2006-April/046191.html http://www.sellsbrothers.com/links/ http://members.tripod.com/IUnknwn/ And there are several old books (a few of which I have copies of) which are also useful references.
This is probably a great project for someone who's really comfortable with pointers and low level stuff. Once the tests you write pass on Windows and find bugs in Wine, the guys who write COM for Wine will fix the bugs, I think. - Dan
-- Wine for Windows ISVs: http://kegel.com/wine/isv