I have decided to start the Haskell on Windows software repository, its located here:
The idea is that Linux users can use their relevant package manager and in one click do "emerge ghc" or something and get GHC installed quickly and easily. For Windows users this means downloading either a .zip or an installer of the project quickly and directly.
The page above just links directly to the most appropriate installation file, and is going to be kept up to date with new versions.
Its kind of depressing to see how few precompiled Windows binaries there are for Haskell programs - only 8, and I compiled 3 of them myself. If anyone has a Haskell project and would like a Windows build contributing please email me, and I'll make a binary and add it to that list.