I know everyone in the community here can get Apache running on their MacBook in the field...but this caught me by surprise doing a firmware upgrade and might help save you some time "googling". I had just upgraded from Lion to Mountain Lion and found Apple removed the web sharing capability from System Preferences. Apache is still there but has to be enabled by the command line...just didn't expect to have it missing after upgrade.
Start/Stop commands and check if running apache (what the gui did, but missing)
sudo apachectl start
sudo apachectl stop
sudo apachectl restart
ps -ef | grep http # check if running ... also go to http://localhost to check
File Locations
/Users/username/Sites/ # http://localhost/~username ...where I put firmware and ONTAP
/etc/apache2/users/username.conf # I had to recreate this file and if any syntax error then apachectl won't start - and won't give an error when it won't start
/etc/apache2/httpd.conf
System Preferences Widget - this puts a GUI system preference button back so you don't have to use the cli... I downloaded and tested it and it works great
http://clickontyler.com/blog/2012/02/web-sharing-mountain-lion/
