Bravo! Bravo! Your maps and now site has made this Greyhawk fan very happy. Consider the site bookmarked.
That megamap is very nice! You might want to consider the new DeepZoom system that's part of the Silverlight 2 beta from MS. It's a tool that makes it pretty easy create a "level of detail" type of system that seamlessly shifts the viewer to higher and higher resolution maps as they zoom in. I use it on for my personal map (which is 12000 x 15000 pixels...but is copyrighted by someone else so I can't publish on the web.) The effect is very like Google Earth, but I found it easier to setup.
Try it out using this software or on the Hard Rock Memorabilia site.
But anyway, that's a very nice map. I look forward to seeing more!