Guys, the most common way to use multi-monitor support is by using the many dual-head cards out there that support two monitors simply with the one card. Win2k/XP handles this easily. In addition, simply adding another PCI card on top of your existing AGP card will give you another monitor to use as well. No big deal. In fact, I believe most of the new GeForce 4's support this in the reference design.
That said, there is very little I would find acceptable to allow for multi-monitor use. Basically, allowing anything other than the radio buffer or possibly the clipboard on the second monitor would not be equitable to the majority who only have one monitor. Still, I'd love to be able to throw my old Voodoo 3 PCI card in my gaming box and run my toejamty old 15" monitor as my radio buffer. That would rock. Now that there are 400+ folks in the main on a regular basis, you almost NEED a full screen radio buffer.
Because of the way the clipboard is implemented, I doubt it would lend itself to being moved to a different monitor very well though.
Also it sounds like this is not a trivial thing to do. Based on the fact that I don't know of any other games that support dual monitors, I'm thinking it's a difficult trick to make it work. I think MS flight sim does this, but that's the only one I could think of. If it was something quick and easy, I'm sure you'd see this feature popping up as a bonus in lots of games..... the fact that it doesn't suggests it's quite difficult. I'd rather have a P-47N or the new bomber updates instead.