NY Daily News Photo Essay -- one of the best ones thus far.
Ultra Radio Photo Essay -- another awesome one.
Scripting News has been the best consistent source of news on the events I have read yet. Lots of quotes from readers and important people as well as links to relevant sites and news stories.
Metafilter has a lot of running posts with a lot of links and personal stories.
BBC Online is an amazing general source of news and for a slightly international perspective.
Blogger's search page for the words "World Trade" on all the blogs through their site.