Converting HTML to Wikka Markup
Please feel free to add to this list
Here's a site that hosts a CGI script to convert from HTML to Wikka markup (as well as a number of other wiki "dialects"):
http://toolserver.org/~diberri/cgi-bin/html2wiki/index.cgi (thanks, JavaWoman!)
A Perl module exists that performs the same functionality (in fact, the link above is hosted by the author of the Perl module):
http://search.cpan.org/~diberri/HTML-WikiConverter-0.68/lib/HTML/WikiConverter.pm
Here's a Perl module that converts pod (Perl documentation markup) to Wikka markup:
http://search.cpan.org/~dstaal/Pod-Simple-Wiki-Wikka-0.09/lib/Pod/Simple/Wiki/Wikka.pm
A Wikka handler that strips down a Wikka-generated page to basic HTML (i.e., no headers/footers/internal links). Note: Will be included in the Wikka 1.2 release.