I love a good opening, ending or insert song. Tell me the songs that really suck with you. The ones where days after you completed a drama you're still humming the tune.

Here are some that really stuck with me:
Mei-chan no Shitsuji (opening)- Rock'a'Trench - My Sunshine
Heartstrings (insert) - Jung Yong Hwa - You've Fallen for Me
Big (insert)- Venny - Hey U  for this one I only watched 1/2 the drama but more than 2 years later i still regularly listened to this song. (i have since finished it!)
Hana Kimi Taiwan (opening) - S. H. E. - Zen Me Ban

What songs stuck with you?

Planetarium by Otsuka Ai from Hana Yori Dango

Eternal Love by Michael Learns to Rock from Healer

@cherry bunny I really enjoyed Eternal Love too, but ever time i heard it i was distracted wondering about the lyrics 'my heart's aflame, and it's burning in your name'

Every time this line was sung i was wondering if it was 'my heart's aflame' meaning my heart is on fire or 'my heart's a flame' meaning my heart is literally fire. Ahh, semantics...sometimes I'm way to distracted by it.
Everthing from Amachan! *lol* Seriously, even a long time after completing it, I still find myself hummimg all those silly songs.
Heres a couple that i really really loved and they stuck with me ♥

Seo Dong ost (Joy)
https://www.youtube.com/watch?v=332wpv06dH0

Love Around' OST: Come Back to Me
https://www.youtube.com/watch?v=xk75ipG8GpA

Mafia Luerd Mungkorn: Suer ost
https://www.youtube.com/watch?v=7Oh14qmZdC4

Shoot For The Stars theme:
https://www.youtube.com/watch?v=_1xLhxVFk3k
 
Who Are You - School 2015 -reset
https://www.youtube.com/watch?v=mpyVBkqGaFk

The Heirs Theme Song - Love Is Feeling
https://www.youtube.com/watch?v=T3ZvqyQmTOU

You Who Came From the Stars -My Destiny
https://www.youtube.com/watch?v=8g_n1cQlVTo

Kill Me Heal Me ost- Auditory Hallucination
https://www.youtube.com/watch?v=ya0nm7unMQo

Scholar Who Walks the Night OST- Secret Paradise
https://www.youtube.com/watch?v=KFf4Qy-uxU8


Most tracks from IWGP
My favorites that I just can't get outta my head:

Roy Fun Tawan Duerd: Khon Mai Dee
Lan Ling Wang: ost
The master's sun: Crazy of you
Love, now: I wanna make a movie about you
Love, now: ost
Boys over flowers: What do I do?
Boys over flowers: Fight the bad feeling
Autumn's concerto: I love him
Ring ring bell: happiness
Rich man poor woman: ost
Skip beat: S.O.L.O.
Khun Chai Puttipat: ost
Fated to love you: Goodbye my love
Kill me heal me: Auditory hallucination
That winter the wind blows: Winter love
Loving, never forgetting: What to do
Loving, never forgetting: I understand
Healer: Eternal love
Sweet sweet bodyguard: ost
There's so many~ I'm sure I've forgotten a lot of great OST's already and my list here only has rather recent ones:

I Hear Your Voice: Every Single Day - Echo
Gu Family Book: Yisabel - My Eden
Producer: Zitten - TV Show
My Beautiful Bride: Steelheart - Stay and Elsa Kopf - Days and Moons
Let's Eat: 케이준 - 식사를합시다
Gaksital: Ulala Session - Goodbye Day
The Virus: Loco, Havy T - The Virus
All the songs in It's Okay That's Love. They were awesome.