Hacki's Ultima Page is the only Ultima website dedicated to nitpicking the Ultima series, i.e. discovering every little fault in the games. This site is an extensive archive of Ultima nitpicks submitted by many different people; anyone can submit a nitpick, though there are a few simple rules to prevent it from getting boring (no nitpicking of bugs, for example).
Hacki's Ultima Page started off by aggressively nitpicking Ultima 9, to prove what a poor game it is. For fun, the nitpicking tradition was eventually extended to all the other Ultimas.
Ultima Info is one of the greatest Ultima resource sites on the net, originally maintained by one of the most knowledgable dragons. There are many parts to Ultima Info, including a maps section, an archive of Micro Dragon's once-lost documentation and other useful sections. But the most prominent is The Other Codex, containing general information about all the Ultimas. Much useful information is provided by Paulon himself, and he also links to external resources.
The Ultima Web Archive is the official Ultima information archive - one of the oldest resource sites, and has not been updated in years, but can still be useful. The FTP archive contains other stuff that doesn't appear on the actual website.
