Ion is a tiling (no overlapping windows) window manager that also has PWM-style tabbed frames which can contain multiple client windows. These features help to keep windows organized and to switch quickly between them. Ion was designed primarily as an efficient and unobtrusive window manager for users who prefer the keyboard.
Jellybean is a Perl Object server that allows people to write custom applications following a simple interface and framework. It's conceptually similar to Zope, but has peer communication potential. It has its own tiny Web server which serves static pages, CGIs, or transforms URIs into method calls on objects, and allows users to create their own behavior.
Kmy-regex is an regular expression library for Java. It can compile a regular expression into bytecode and then load it into JVM on the fly. In the environments where class loading is not an option (such as applets) it can produce an interpreted (but slower) form of the regular expression.