Merhaba - Turkish

Privet! - in Russian
Salut! - in Romanian
Noroc! - in Romanian

Merhaba - Turkish
Privet! Salut! Noroc - Romanian
good job

Ok then
Merhaba - Turkish
Privet! - Russian
Salut! Noroc - Romanian

γεια χαρά (ya hara) - hi
or
καλημέρα(kalimera) - good morning

from Greece

cantonese.......你好(sounds like: nei hou)
mandarin.......the same written words你好 (but different pronounciation: ni hao)
interesting~

CZEŚĆ-in polish language

Bonjour - French
Bonjourno - Italian
Güten Morgan - German
Buenos Dias - Spanish

Like the Chinese ones - the on of only two words I can speak in Chinese (Ni How) and Thankyou - (shi shi) oh I forgot (champay) like bottoms up, cheers, with a drink, you finish it in on go.

In albanian language here are some greetings:

Miremengjes-Good Morning

Tungjatjeta-I wish you a long life(the exact translation) or Hello

Mirupafshim-Good bye

Naten e mire-Good night

Diten e mire-Good day

In swedish we say:

Hej!

Ever considered replying someone who says 'hello!' to you by sayıng 'two hellos to you!'

Well, Arabs do...Merhaba is a common hello in Arabic too, and the usual reply is Merhabteyn (which means 2 hellos)

Zdoroven'ki buly! - in Ukranian

Buna - Romanian
Salut - Romanian

Merhaba - turkish

"Hello"
"Hi"

Sawasdee ( thai )

Hallå! (swedish)

你好= selam in chinese-tapei
こんにちは = selam in japanese

ya da ben sallıyorum hehe

bide bunlar var

Privet! = selam in russian
hola= selam en espanol
ciao = selam in italiano

in dutch:

Goedendag - Iyi Günler

Goedemorgen - Günaydın

Goedemiddag - Tünaydın

Goedenavond - Iyi Akşamlar

Goedenacht - Iyi geceler

Hallo / Hoi - Merhaba

Selam - Hi

Apa Khabar - How Are You

Selamat Pagi- Good Morning

Selamat Petang- Good Evening

Selamat Malam- Good NIght

Selamat Datang- Welcome


Malay Language from Malaysia

Ćao - Serbian

Здраво - Zdravo - Hello from Macedonia

Hei! - Norwegian

Quoting libralady

Bonjour - French Bonjourno - Italian Güten Morgan - German Buenos Dias - Spanish Like the Chinese ones - the on of only two words I can speak in Chinese (Ni How) and Thankyou - (shi shi) oh I forgot (champay) like bottoms up, cheers, with a drink, you finish it in on go.

I don´t agree to the German one. 

Firstly, it´s actually written "Guten Morgen" and secondly it means good morning and not good day/hello like the others :S no offense (even though bonjour etc. can be used with the meaning good morning, I guess you rather meant hello in general, which would make Guten Morgen wrong in this case; if you really meant good morning, I apologize.) 

So German:

Hallo - Hello/Merhaba

Guten Morgen - Good morning/Günaydın

Guten Tag - (Good day)/İyi günler

Guten Abend - Good evening/İyi akşamlar

Gute Nacht - Good night/İyi geceler

Hi - Hi/Selam

Buna - romanian

Servus - romanian (Transylvania)