Java port of Oniguruma: http://www.geocities.jp/kosako3/oniguruma that uses byte arrays directly instead of java Strings and chars

Byte based encoding support library for java

An abstracted interface to invoking native functions from java

Java wrapper around libffi

A servlet bridge for (Ruby-based) Rack applications that allow them to run in Java Application servers using JRuby.

JZlib is a re-implementation of zlib in pure Java

JvYAMLb is a YAML processing library for Java, used by JRuby

Lookup TCP and UDP services from java

Java portion of JRuby Prism parser support.

A pure-java X86 and X86_64 assembler