Ask HN: Which tool do you use to create beautiful diagrams?

Ask HN: Which tool do you use to create beautiful diagrams?
623 by lichtenberger | 199 comments
For instance what they use for stuff like http://bit.ly/1Jpb9zO Or I don't know how to describe it, because right now I can't find an example, but more "comic" like maybe. I know that Venka Subramanian once had such a nice article about Akka with beautiful diagrams, but can't find it either :(