formfind – a command line utility in perl, that comes with curl; it reads its input from STDIN; it is completely stand-alone; it has been my preferred utility for this purpose for a long time
mech-dump – a command line utility in perl, that comes with perl’s WWW::Mechanize, and it needs the later one installed
Michael Schrenk‘s form_analyzer.php – online – you replace the original form action URL with this URL, trigger submit in your browser, and wait for a nicely formatted HTML page displayed in your browser. of course I trust Michael Schrenk, but you might have valuable contents in your HTML, so think twice, whether you want to leave it to somebody else, that you don’t know at all.