There is a similar thread for the Japanese language in the 'General Japan Talk' section so I created one for the Korean :D The title speaks for itself!

Well, mine are...
Aigoo
I really like it when the characters in a drama say this. I myself say it sometimes when something goes wrong :P

Yah!
The Korean alternative for 'Hey' or 'Oi'. I guess girls say it the best; like in: "Yah! Are you dumb?", "Yah! Who do you think you are?" xD

[i]Annyeong, Komayo and Mian heyo[i]
Basic words for 'Hello, 'Thank you' and 'I am sorry' respectively. I like the way they are said, like 'Annyeong' is usually said in rhythm by some cheerful, over-friendly sort of characters.

For now I can only remember these. I'll post some others if I can remember them later.
Let's hear from you guys :)
mine are: (i even use these...)

- aigoo
- aish!
- oppaaaaaa~~ (i use it on twitter only)
- nuna/noona (i just like the way cute korean boys says it)
- hyung (same reason as above)
- OMO!
Alreseo - Alright
OMO!
Aish!
Aigoo
Bienhaeyo - I'm Sorry
Swis! - like I described in another thread, it's that sucking in of the breath where they are expressing "Do as I say!" or "hush it you!" (I love that)
Haha, I use Aigoo and Omo all the time now. My brother looks at me weird every time I do.

I really like the Korean language and can now watch an episode without subs and get the gist of what they are saying.
Nice thread Rika! I actually was planning to start this thread in Korean section as well but then I kinda forgot about it… So good that you started it instead! :)

Here are some expressions that came to my mind right away:

-Omo, Aigoo! Standard drama expressions that I use frequently nowadays. And I get strange looks from family members as well :P
-Eomma 엄마. Mom. I like the sound of this word. I like the way it feels when you pronounce it. Round and soft.
-Jinjja! 진짜! Really! I use this one frequently as well. Said often with good grimace and cursing tone.
-Shirho 싫어. I hate/I don’t want. Though it’s a quite harsh and rude way to express negation, I really like how it sounds and the tone it is usually uttered with.
-Kwaenchanayo. 괜찮아요. It’s okay/I’m okay etc. I like the way it sounds and how it can be used in many different situations.
-Chohahaeyo.좋아해요. I like (it/you). I still remember that I learned this expression after watching one particular scene in “You’re Beautiful”. :)

I also like all the verbs with the formal ending “hamnida” like in “kamsahamnida, saranghamnida” etc.
Aigoo, I think I could list here about all the Korean words I know because all the Korean words sound so nice to me atm. But I’ll stop here for now. :)
I actually kind of like it when they greet each other with "Wasseo?", which means "You came?" I just like how nonchalant it seems, like, "Oh, you came? Good job, you ---here's a cookie." But my favorite expression has to be the Konglish "Weon shyat!", or "One shot!" because at heart I'm actually a frat boy who loves to make my drinking buddies chug their beer or soju as the case may be. And I'm one known to knock back a few shots as well. (TMI?)
Chohahaeyo

Ottoke = what should i do :P

Oppa = to a brother or an older brother.. not a whinny one pls :P

Ommo

Hyung

Nunna

YA !!!! ... in a shouting manner :P
i laso like.. WHYY?? WHY ? WHY !...
I just thought of one. When really frustrated with someone, and wanting them to leave yell repeatedly "Na gah! Na gah! Na gahragu!"
I remembered this one just now- the suffixes aa and shii they add after someone's name.
Like in: Woo Ri-aa and Cha Dong Joo-shii

I also like Ottoke and Chohaheyo as mentioned by Biya and Susu.
Saranghae
Ottoke
Unnie
Kumao
Omo
I like all the sounds that show they are upset or frustrated with someone. I especially like the emotion put into the words.
But there is one word I fell in love with whilst watching You're Beautiful and this word has started my love with the Korean language - geu reom. It sounds almost like Krom or Crom but has more body to the word when it is being spoken.
OHO!!!! - heard it in some dramas but the first time i actually took notice of it n it registered in my head was when Lee Sul/ Kim Tae-Hee used it in My Princess (she used it quite often)..dunno if I'm gettin the spellin correct though
GESEKI - son of bitch
Shibbal - fuck