I have several. I'll list them by game. Usually these parts are when I accomplish something challeging
Ocarina of Time
1) Beating the Water Temple
2) Beating Morpha (using the platforms only)
3) Beating Twinrova
4) Beating Ganondorf
5) Beating Ganon
6) Beating Dark Link without the Biggoron's Sword
7) Successfully climbing up the spiral ramp to the Megaton Hammer
8) Getting the Zora's Sapphire
9) Beating the Forest Temple
10) Beating Phantom Ganon
11) Finishing the game with three Heart Containers
12) Finishing the game with three Heart Containers, default Magic Meter, no optional items, default ammo, only one bottle with nothing in it, defeating all the bosses the legit way, and finishing the temples out of order
13) Beating the Kakariko Well
14) Beating the Shadow Temple
15) Meeting Zelda
16) Getting a Medallion
17) Finishing the game with all the Gold Skultulas
18) Finishing the game 100%
Majora's Mask
1) Reverting to hylian form
2) Getting a new mask
3) Easing the pain of Darmani/Mikau
4) Getting a new entrance song
5) Getting the Ocarina back
6) Clearing a Temple
7) Clearing the Anju and Kafei Quest
8) Finishing the game 100%
9) Getting the Fierce Deity Mask
10) Beating Odalwa
11) Getting Epona back
12) Clearing the Swamp Temple
13) Clearing the Snowhead Temple
14) Defeating Odalwa
15) Defeating Majora without the Fierce Deity Mask
16) Getting drunk on Chateu Romani
A Link to the Past
1) Getting the Master Sword
2) Killing Aghanim
3) Killing Ganon
4) Finishing the game 100%
And that's all for now because I'm lazy.