Outside of this one, I would have to say
www.classicamiga.com. Can't say I'm a big fan of the new CMS system that the site has, but I know there has been lots of stuff added over the last year or two, whereas it was a bit neglected before. It is due to the not-quite-as-good-as-it-could-be CMS that makes me not want to look for stuff on there normally. The forum always has plenty of helpful people on it and is a good place to get answers to questions.
Besides Classicamiga, I also like Greg Donner's Workbench Nostalgia pages (
www.gregdonner.org)
Can I also vote for my own website,
www.stevecoates.net ? There is hardly anything on it at the moment, but I do intend to put some of my own amiga related content on it eventually.