JGraph is the most powerful, lightweight, feature-rich, and thoroughly documented open-source graph component available for Java. See the project homepage at www.jgraph.com for information and downloads.
ahahaha. Just love the review below. A DLL for a Java Swing product? And you were trying to buy a free product from a salesman? Totally unfair to question your competence there... Classic :D.
Pathetic sales support. A very rude sales person. The download doesn't contain the required DLLs and the sales person starts questioning your competency and suggests another product...
Wonderful component. Easy to use yet very powerful.