Erorus sent us some cool Armory-related tools he's been working on -- you can find them all at QuickArmory.com. Aside from the usual Armory lookup (with a much faster loading design), he's got an Heirloom item tracker (you put in your level and it will show you what the Heirloom items look like throughout the game), an Arena Points calculator, and perhaps most interesting, an Achievement Tracker. That last one actually does something a little different from most Armory sites -- it uses the Greasemonkey Firefox script to have your browser pull information from the Armory rather than Erorus' servers doing it. The output ends up looking more or less the same, but basically his site tells your browser what information to get, and your browser gets the info rather than his server. Interesting way of getting around the problem of stability, though the tradeoff is that you've got to use Firefox and install the addon to use his site.
Allows you to customize the way a webpage displays using small bits of JavaScript.
Hundreds of scripts, for a wide variety of popular sites, are already available at http://userscripts.org.
You can write your own scripts, too. Check out http://wiki.greasespot.net/ to get started.
None of the tools provide quite as much functionality as some of the other more specialized Armory sites out there, but Erorus does some new and interesting things with the Armory information, on the Achievement tracker especially. If you can't get enough of your character's stats (and in this case, happen to also use Firefox), they're worth checking out.