Just to say hello!

Marhaba..................................................................................................................[Arabic]
Es salaam aleikom .................................................................................................[Arabic again]
Namoskar................................................................................................................[Bengali]
Neilhou.....................................................................................................................[Chinese]
Halo..........................................................................................................................[Dutch]
Iiti.............................................................................................................................[Egyptian]
Hello ........................................................................................................................[English]
Hi..............................................................................................................................[English again]
Welcome..................................................................................................................[English again again]
Howdy/G'Day/Greetings.........................................................................................[(ok your guess)]
Bonjour ...................................................................................................................[French]
Hallo.........................................................................................................................[German]
Namaste ................................................................................................................ [Hindi]
Buon Giorno ...........................................................................................................[Italian]
Salam ......................................................................................................................[Kashmiri]
Namaskaaru ..........................................................................................................[Konkani]
Namaskaram..........................................................................................................[Malayalam/Telugu]
Sat sri akaal ...........................................................................................................[Punjabi]
Kem cho..................................................................................................................[Gujarati]
Namaskara.............................................................................................................[Kannada]
Ola...........................................................................................................................[Portugese]
Hola ........................................................................................................................[Spanish]
Vannakam..............................................................................................................[Tamil]
Suswagatam ..........................................................................................................[Sanskirit]
__/\__ ..................................................................................................................[Sign Language]
Salaam alekum .....................................................................................................[Urdu]
Dydd da..................................................................................................................[Welsh]
Sawubona...............................................................................................................[Zulu]

Some of the popularised ones:

Aye Muralilal, pehchana nahi?.............................................................................[Anand]
Wats up doc? ........................................................................................................[Bugs Bunny]
Kya hero!...............................................................................................................[Friend]
Kya zero!................................................................................................................[(close) Friend]
How you doing? ....................................................................................................[Joey Tribiani]
Hey ya....................................................................................................................[Karthik]
Hello, is it me your looking for?.............................................................................[Lionel Richie]
Wassaaaa............................................................................................................... [Umm ...Me!]
Salaam Namaste...................................................................................................[Nikhil Arora/Ambar Malhotra]
Hello main Raj, naam to suna hoga ......................................................................[Surinder Sahni]
Hi dear, want to do frandship plz?........................................................................[!]

And the award for the best hello:-

Woof woof .............................................................................................................[My Neighbour's dog]