This Rugby Logotype Comparison is a great “illustration” of the way Flickr facilitates an ongoing visual conversation.
I don’t know anything about these folks, but there’s a Stanford Visual Language Project that seems to be exploring the relationship between textual and visual communication. There’s also a mailing list.
FEED on the semiotics of color in pedestrian warning signs (or something like that). I love FEED mag.
Basic Color and Design SBFAQ (“Should Be FAQ”). Some absolutely useful and interesting info (i.e. way more than you need to know about color).