I got a lot of bug reports about broken POD internal links, so I searched on CPAN for something to check these automatically, and found this. I am using this module to check POD before uploading to CPAN. It finds broken internal links as well as other kinds of errors, like forgetting to put =back after =over. It seems to be easy to use and works well. I had to remove some warnings about empty lines containing whitespace though, since the empty lines are within example code blocks.