Dave Yost's Web Site (of course)
General Electric, Amazon.com, Borders.com, About.com, ibm.com - among the first I heard to drop the "www." in radio announcements
Apple - They're finally thinking different on this, but not advertising it, amazingly.
Web.Org.UK - an early proponent of "web." instead of "www.".
Massachusetts Institute of Technology - They had an interesting "www." vs. "web." split (see part of the story on this)
Bay Area Internet Solutions (my ISP - they enable access to all customers' www domains without the www.)
W.W. Norton - Previous prize holder for WWW.WWNorton.com (see the story on this)
About half who were early adopters of the "web." alternative have added access without either "web." or "www."