I created the word cloud library, Kumo (Cloud in Japanese), in Java. Oddly, I've always liked word clouds. :)
Kumo can generate BufferedImages, image files (PNG,BMP,etc), and also has examples showing usage in JPanels. The project is mavenized and in Maven Central to make integration easier. Below are a few example word clouds and there are more examples on Kumo's GitHub page: https://github.com/kennycason/kumo
There is also a JPanel example here and a screenshot here.
