txt2html is a Perl program that uses the HTML::TextToHTML perl module to convert plain text to HTML. It supports headings, lists, tables, simple character markup, hyperlinking and is highly customizable. It recognizes some of the apparent structure of the source document (mostly whitespace and typographic layout) and attempts to mark that structure explicitly using HTML.
The HTML::Defaultify Perl module is designed to allow CGI programmers to present forms with some fields filled in, which is handy for letting users correct bad input, show records to be edited, and much more. The main function, defaultify(), takes any block of HTML and a hash of field names and values, and returns the HTML with the form fields set to those values. Value lists for multiple same-named fields are supported, as are pages with multiple forms. Several different input formats are supported for compatibility with existing tools.