Google Robots.txt tool
Posted February 9th, 2006 by Max Chirkov
Google Sitemaps team added another cool feature to sitemaps accounts - Analysis of cached robots.txt. Very nice tool - allows you to play with your robots.txt file without actually changing it on your site. It checks if Google can crawl specific URLs or they are being blocked by robots.txt and it gives you quick analyses. This tool helped me to solve my robots.txt problem I couldn't figure out for over then a year now. Very nice.
For more information read Matt Cutts post and Google Sitemaps Blog.