[chmodd]

MD5 is so fast on GPUs, you can do some pretty ridiculous dictionary attacks in a matter of minutes (like trying every combination of words that has ever been written in a book or posted online - using google's n-gram corpus for example). Then you have plenty of time to try letter substitutions (3 for e), combinations such as word + number + word, etc. This doesn't apply of course, if your password is a long string of random characters.