robots.wizard(tm)

robots.wizard(tm) is an open source (PHP), web-based, robots.txt generator and editor with a nice interface that allows you to browse the file system and check the boxes of files and directories you would like to disallow. It allows you to efficiently generate accurate robots.txt files and provides a powerful server-side reference checker. It includes authentication to limit access to the site directory structure. The product and code are well-documented. Updated for improved security.