I think I've seen this talked about before, from what I remember I don't think it's possible with the current version of WinUAE due to the way TCP/IP is implemented... the Amiga doesn't get it's own IP, and Windows has no idea what incoming ports should be forwarded to the WinUAE TCP/IP stack. The way WinUAE works right now, there's no way to forward anything incoming to WinUAE's stack.
Maybe this has changed, but I don't remember ever seeing it mentioned in the changelogs.
On another note, has anyone tried Amiga Apache on Amithlon yet? That would be a nifty little server
