This site is powered by the
XKPasswd.pm Perl Module, and serves as a good example of its capabilities. The module has been released under the
FreeBSD license, so it's completely free to use, even within commercial products, providing the two terms of the FreeBSD license are observed. Bascially,
you can re-use the library as long as credit is given, the author's copyright notices are preserved, and you promise not to take legal action against the
author if the code gives you problems.
The module can be downloaded from the author's website: www.bartb.ie/xkpasswd.