As the CEO of a famous operating system company once said, "I have four words for you: developers, Developers, DEVELOPERS, DEVELOPERS!" ( http://www.youtube.com/watch?v=KMU0tzLwhbE )
Attracting more developers (not of wine, but of their own apps) to Linux by getting their IDEs running on Wine would be great for wine, as developers are more likely than the average user to file bug reports or (dare we hope) fix bugs. So it would be good to get popular IDEs working on Wine.
Newer Microsoft IDEs like Visual Studio 2005 are a challenge, Visual Studio 2005 express requires BITS (which is a SoC project in itself, http://bugs.winehq.org/show_bug.cgi?id=5054)
Some IDEs run fairly well if you install DCOM98, in which case you would write conformance tests exposing the problems in our COM implementation so Rob can fix them :-) Older IDEs like Visual C++ 6 and Visual Basic 6 are in this category. cf. http://bugs.winehq.org/show_bug.cgi?id=4931 http://bugs.winehq.org/show_bug.cgi?id=5321
And then there's Eclipse, Delphi, Turbo C++, IntelliJ, Powerbuilder, Access, Visual Fox Pro, and many others. There are also specialized IDEs like AVRStudio (an IDE for embedded developers) which people want to run in Wine (see http://bugs.winehq.org/show_bug.cgi?id=5312).
Picking one or two of these and focusing on getting its problems solved might be very useful. - Dan