Really Cool Photo Blog:
If you like old black & white photographs, you'll love the photo blog Shorpy.com. It features new photos every day, very high resolution, mostly of American life in the early 20th century (and mostly around Washington, DC). It's super-cool stuff: I started visiting it about a week ago, and it's been a treat every day. Also note that each post has a "view full size" option that expands the photo. Hat tip: Eck.