Cross-platform, interactive shell with standard UNIX utilities. Pure Bash syntax via Dhaka or Treetop. Interfaces in GTK, WxRuby, and FXRuby.
Commands are just ordinary Ruby scripts, so it's easy to write your own. On UNIX systems, the path automatically includes places like /usr/bin so you can use the same great command line utilities as any other shell.
Highly configurable, very modularized.
Always looking for developers. See http://rubyunix.rubyforge.org/contribute