Wow, that is freaking awesome. You should make it into a base of sorts and call it Castle Grayskull!!!!
You know, the nether in SMP is a strange topic. In single player, I always used many nether portals to allow fast travel across vast distances in my worlds. In SMP we can simply /warp Bootybay or /home and so on. Fast travel is really the only reason to go to the nether, other than to get a few mats. It will be good to have it working in SMP after 1.6, I just don't know if I'll care or not...
Unless we decide to build a nether village next to a lava lake. Then I'll go, lol. Notch really needs to add some more incentive into the nether, something like a special ore that could persuade us to build nether mines, or a special mushroom that only grows on soul sand, or a new nether mob that is rare and drops diamonds, or hell hounds that we can tame as pets...