There are many different Arabic greetings, depending on your specific location.
(North Africa, Middle East) - Marhaba
(North Africa, Middle East) - Ahalan
(North Africa, Middle East) - Es salaam aleikom
(North Africa, Middle East) - Salaam
(North Africa) - Ahlen
(North Africa) - Ahlan
(Algeria) [informal] - Labass
(Egypt) - Ahlan wa sahlan
(Egypt) [informal] - Sa'ida
Iraq) [informal] - Halaw
(Morocco) - Ahlen
(Morocco) - Ssalamu 'lekum
(Morocco) - Labas

I found all these at the site listed below. There is a lot more information there as well.
Good luck!