ctioga2 is a command-line plotting utility. It
enables users to make publication-quality plots of
data and mathematical functions quickly. It is a complete rewrite of the old ctioga, and is much more flexible, with quite a few additional features.
jplot2d is a high-performance multi-threaded 2D plot library. It produces publication-quality plots. It's thread-safe and can run in headless mode, fitting in a servlet container. It has a multi-thread rendering engine and contains swing and swt GUI components.