I do most of my development in FireFox on OSX. Today I've been testing some javascript widgets from HelpSpot in Safari and running into some trouble. Unfortunately I couldn't find any way to enable a javascript debugging console in Safari. After a little bit of hunting I found that the only way to do it is by issuing this command in Terminal:

defaults write com.apple.Safari IncludeDebugMenu 1

Restart Safari and you're all set. After setting it up I found my bug in literally 1 second.