Let's list them, scripts (actively developed/released publicly):
Wakaba http://wakaba.c3.cx/ (Perl)
Kusaba X http://kusabax.cultnet.net/ (PHP)
Orphereus http://orphereus.anoma.ch/ (Python)
PyIB https://github.com/tslocum/PyIB-Standalone (Python)
Kotoba http://code.google.com/p/kotoba-ib/ (PHP)
TinyIB https://github.com/tslocum/TinyIB (PHP)
Ochan http://code.google.com/p/ochan/ (Java)
Wakarimasen http://git.kiace.com.ar/wakarimasen.git/ (Python)