Something that just came up last week: it might be nice to have a toolchain targeting the win32 platform. The few times I've needed to build a .exe from a linux box were memorable experiences due to the hoop-jumping required. (I suspect it's much easier now.)
Users wondering "how well would such-and-such a program do under Windows?" would then be able to simply apt-get some packages and find out. While providing many generic cross-compilers is almost certainly infeasible, maybe Debian could adopt some of the Cygwin tools? Phil -- If ye love wealth greater than liberty, the tranquility of servitude greater than the animating contest for freedom, go home and leave us in peace. We seek not your counsel, nor your arms. Crouch down and lick the hand that feeds you; and may posterity forget that ye were our countrymen. - Samuel Adams