I was doing some brushing up and learning on ruby on rails and found I had broken MAMP by installing Pow ( a easy to use server for ruby ). I did some searching and happend upon this stackoverflow post.
This helped me about 1/2 of the way, but after completing the steps I was still left with a screen like the one below, on my once-working Mamp sites.
To fix this issue you need to remove the POW firewall rule. First view the current firewall rules.
$ sudo ipfw show
Now you will need to remove the rule on localhost or 127.0.0.1 . For me this command was ( for you it might be different, use the identifier on the beginning of each record line. )
$ sudo ipfw del 00100
After that I uninstalled pow, re-installed pow, Started mamp, and then everything worked. Coolbeans