Let's go through each OSL/KPGA/MSL season one-by-one shall we? I'll try my best to remember storylines and stuff from each.
OSL
PKO '99 - First ever major Starcraft league
Hanaro OSL - First time league on the new OGN channel, first (and only) foreigner to win an OSL (Grrrr...)
Freechal OSL - First OSL played at the Megaweb Studio in COEX, First OSL to have an external venue for the finals. Legend of the Fall is created.
Hanbitsoft OSL - First instance of the 'Royal Roader' (Boxer)
Coca-Cola OSL - First instance of the Lim/Jin-rok Rivalry (Boxer vs Yellow)
SKY 2001 OSL - Legend of the Fall comes back. Third foreigner to play in an OSL (Asmodey, after Pillars and Grrrr...).
NATE OSL - 'The Forgotten OSL' due to the 2002 World Cup running at the same time.
SKY 2002 OSL - Legend of the Fall returns (Reach). Fourth (and last) foreigner in an OSL (ElkY).
Panasonic OSL - Nada royal roads. Last appearance of GARIMTO and many other veterans, signifying the end of the 'first-generation' of Starcraft professionals.
Olympus OSL - Yellow loses opportunity to secure an OSL. Beginning of the 'second-generation' of Starcraft professionals.
mycube OSL - Boxer vs Joyo. Baseball stadium finals. Paradoxx ruined Zergs.
NHN OSL - Silent_Control cheeses his way to 3rd place. Veteran Zeus finally makes it to an OSL final, only to be stopped by Nal_rA.
Gillette OSL - First OSL played in the renovated Megaweb studio. First appearance of iloveoov and JulyZerg, who royal roads this season. Boxer fails to qualify for an OSL for the first time.
EVER 2004 OSL - Boxer returns all the way from the qualifiers to make it to the final, dispatching long-time rival Yellow on the way in dramatic fashion. However, he is stopped by his protege, iloveoov.
IOPS OSL - Second peak of Nada. First league to ever have only one representative of a race (Reach, Protoss).
EVER 2005 OSL - July's second title.
So1 OSL - Golden Mouse created. Boxer's attempts to win the Golden Mouse ended by Royal Roader Anytime, thus resurrecting the myth of The Legend of the Fall.
Shinhan 2005 OSL - First of four OSL's sponsored by Shinhan Bank consecutively. iloveoov sweeps the finals 3-0 vs July.
Shinhan 2006 OSL S1 - First OSL to move to a 24 player tournament. Casy gets luckiest bracket ever and wins.
Shinhan 2006 OSL S2 - Nada eludes personal tragedy and the Legend of the Fall to win the first Golden Mouse trophy. First OSL to be played at the newly built e-Sports Stadium in iPark Mall, Yongsan.
Shinhan 2006 OSL S3 - Savior confirms his 'bonjwa' status by finally winning an OSL title. The 'third-generation' of Starcraft professionals begin to take over.
Daum OSL - Return to the 16 player tournament format. First OSL for 'wonderkid' Flash who places fourth. GGPlay is the first ever player to win a final down two sets.
EVER 2007 OSL - Jaedong royal roads. First instance of 'Taek-Bang-Leessang' all appearing in an OSL.
Bacchus 2008 OSL - Flash wins his first OSL title. First instance of a map being removed halfway through the tournament (Demon's Forest).
EVER 2008 OSL - First OSL to introduce the 36-man format. July comes out of nowhere and acquires the second Golden Mouse.
Incruit OSL - After two second-place finishes, Stork finally wins an OSL. Fantasy revolutionizes TvZ with his mech build.
Batoo OSL - Fantasy loses his second consecutive OSL final.
Bacchus 2009 OSL - Jaedong acquires the third Golden Mouse and is the first back-to-back champion since Boxer in 2001.
EVER 2009 OSL - Flash dominates the competition and marks the beginning of his 'god' reign.
Korean Air OSL S1 - Greatest OSL finals venue ever? Effort takes the surprise win over Flash.
Korean Air OSL S2 - First OSL finals overseas (Shanghai, China). First (and only) Leessang OSL final. Flash claims the fourth (and final) Golden Mouse.
Bacchus 2010 OSL - Fantasy finally wins an OSL.
Jin Air OSL - First OSL after a six month hiatus. Return to the 16 man format. Jangbi fulfills Legend of the Fall.
tving OSL - The last Starleague. First ever back-to-back finalists. Consecutive wins for Jangbi.
KPGA/MSL
KPGA 1st Tour - Dunno?
Reebok KPGA - Beginning of Nada's first dominance era.
Pepsi Twist KPGA - It's Nada again.
Baskin and Robbins KPGA - Nada wins three in a row, foreshadows what would happen again in the Panasonic OSL a few weeks later.
Stout MSL - First MSL since geMBC rebrands to MBCgame, new studio at Sejong Game World. New double-elimination tournament format.
TriGem MSL - Yellow once again fails to win a major title. Beginning of iloveoov's period of dominance.
HanaFOS CenGame MSL - Dunno?
SPRIS MSL - Nal_rA recall game.
You Are The Golf King MSL - First (and only) MSL final that was Bo7.
UZOO MSL - Beginning of sAviOr's dominance era.
CYON MSL - Dunno?
Pringles MSL S1 - Format change to Ro16 dual-tournament format. First MSL in newly renovated studio at Sejong Game World.
Pringles MSL S2 - sAviOr's third title.
GOMTV MSL S1 - 3/3 revolution. sAviOr falls from grace. Beginning of 18 month sponsorship by GOMTV. First MSL in new studio at COEX.
GOMTV MSL S2 - Bisu wins back to back MSL's. Format changes to Ro32.
GOMTV MSL S3 - Mind upsets Bisu in finals.
GOMTV MSL S4 - Jaedong wins first MSL.
Arena MSL - First MSL in new studio at LOOX. Birth of 'the pretender'.
ClubDay Online MSL - Bisu earns third MSL title.
Lost Saga MSL -
Avalon MSL - Zerg mirrors all day.
NATE MSL - Infamous power outage final.
Hana Daetoo Securities MSL -
Bigfile MSL - Awesome semi-finals.
PDPOP MSL -
ABC Mart MSL - The last ever MSL.
Personally for me;
Best OSL - EVER 2004, but tving has a really close spot to my heart because I was there for the semi-finals and finals live in person.
Best MSL - Bigfile MSL
+ Show Spoiler [스폰서 캐치프레이즈 (Ignore pls)] +
스마트폰의 시작, 마이큐브! The start of the smartphone, mycube!
따라올 수 없는 재미, 한게임! Unmatched fun, Hangame!
내 생애 첫 면도는 질레트와 함께! / 넘버 원은 넘버 원 다워야 한다, 질레트! Your first and only shave should be Gillette! / Number one is supposed to be number one, Gillette!
나를 새롭게 만드는 휴대폰, EVER! Create me a new cell phone, EVER!
보여주고 싶은 MP3, IOPS! Show me your MP3 player, IOPS!
나를 새롭게 하는 휴대폰, EVER! My new cell phone, EVER!
모든 휴대폰은 So1에서 만난다, 오픈 모바일 So1! Meet all the cell phones at So1, Open Mobile So1!
처음부터 끝까지 함께하는 신한은행! Together from the beginning to the end, Shinhan Bank!
도전하는 젊음과 함께하는 더 큰 감동! The challenge of youth, and an even bigger sensation that everyone experiences!
UCC 세상, 다음! UCC World, Daum!
세상의 SHOW, 에버와 즐겨라! World's SHOW, enjoy EVER!
지치지 않는 열정, 박카스! Tireless enthusiasm, Bacchus!
더하는 즐거움, 함께 나누는 감동, EVER! Attaching pleasure in sharing emotion, EVER!
나만의 취업전략, 인크루트! My own employment strategy, Incruit!
이제는 바투 한판! Play Batoo now!
나를 강하게 하는 친구, 박카스! Be stronger with friends, Bacchus!
유쾌한 상상, 넘치는 즐거움, EVER! Imagine delight and enjoyment, EVER!
새로운 세상을 여는 첫 걸음, 대한항공! The first step in opening a whole new world, Korean Air!
꿈을 향한 비상, 대한항공! Flying towards a dream, Korean Air!
당신의 진짜 피로 회복제, 박카스! The real remedy to fatigue, Bacchus!
색다른 도전의 시작, 진에어! The beginning of a different challenge, Jin Air!
세상의 모든 동영상을 담다, 티빙! All of the world's videos in a box, Tving!
따라올 수 없는 재미, 한게임! Unmatched fun, Hangame!
내 생애 첫 면도는 질레트와 함께! / 넘버 원은 넘버 원 다워야 한다, 질레트! Your first and only shave should be Gillette! / Number one is supposed to be number one, Gillette!
나를 새롭게 만드는 휴대폰, EVER! Create me a new cell phone, EVER!
보여주고 싶은 MP3, IOPS! Show me your MP3 player, IOPS!
나를 새롭게 하는 휴대폰, EVER! My new cell phone, EVER!
모든 휴대폰은 So1에서 만난다, 오픈 모바일 So1! Meet all the cell phones at So1, Open Mobile So1!
처음부터 끝까지 함께하는 신한은행! Together from the beginning to the end, Shinhan Bank!
도전하는 젊음과 함께하는 더 큰 감동! The challenge of youth, and an even bigger sensation that everyone experiences!
UCC 세상, 다음! UCC World, Daum!
세상의 SHOW, 에버와 즐겨라! World's SHOW, enjoy EVER!
지치지 않는 열정, 박카스! Tireless enthusiasm, Bacchus!
더하는 즐거움, 함께 나누는 감동, EVER! Attaching pleasure in sharing emotion, EVER!
나만의 취업전략, 인크루트! My own employment strategy, Incruit!
이제는 바투 한판! Play Batoo now!
나를 강하게 하는 친구, 박카스! Be stronger with friends, Bacchus!
유쾌한 상상, 넘치는 즐거움, EVER! Imagine delight and enjoyment, EVER!
새로운 세상을 여는 첫 걸음, 대한항공! The first step in opening a whole new world, Korean Air!
꿈을 향한 비상, 대한항공! Flying towards a dream, Korean Air!
당신의 진짜 피로 회복제, 박카스! The real remedy to fatigue, Bacchus!
색다른 도전의 시작, 진에어! The beginning of a different challenge, Jin Air!
세상의 모든 동영상을 담다, 티빙! All of the world's videos in a box, Tving!