Umm... debugging your code outside your own operating system? The more I think about it, the more it seems like writing your own tools -- compiler, assembler, debugger... is something anyone really serious about their operating system should do. For most, it is a hobby, I suppose and they find that to be a distraction from what they want to do. At some point, however, it will pay-off because you don't need to leave your operating system. It's really not that hard to make a simple unoptimized compiler, say, compared to hacking some hardware device. It's just straight-forward, fun programming. I had a blast writing my compiler -- way more fun then getting hardware devices working. One of the most satisfying things was adding optimizations and watching my code size shrink and things get faster.
If you wish to do kernel mode development, you might be interested in LoseThos,
http://www.losethos.com, my operating system with my compiler. The IDE is not that good, but where else can you freely launch and test code in kernel mode?
It's 64-bit, too. I've never spent much time with virtual machiens, but from what I hear, LoseThos doesn't run in a virtual machine and when I tried it, it was dog slow in qemu and no hardware worked. I can't imagine having to run in a virtual machine. I love being 100% independent from other operating systems. Virtual machine software is probably holding you back in ways you don't know.
You guys are still developing new 32-bit code, from what I understand! That's insane. LoseThos is 100% 64-bit with no legacy stuff.