I've started noticing that bike companies often have "signatures" of various sorts. Bianchi Celeste may be the most famous of these -- not every Bianchi is Celeste, but if it's Celeste, it's a Bianchi. There are threads on the Classic and Vintage forum about the patterns different old-school framebuilders worked into lugs. Specialized likes to put a little arch into top tubes, Marin uses angled tubing.
What are some other brands' signatures?