Title says it all :D
Here's the list of my favourite Anime music... ( Well , I may have forgotten a few... )
Title of Music ------- Anime it's from ------- Opening or Ending or BGM ( Background Music )
Colors ------ Code Geass : Lelouch of the Rebellion / Hangyaku no Lelouch ------- Opening
Mosaic Kakera ----- Code Geass : Lelouch of the Rebellion ------ Ending
World End ------ Code Geass : Lelouch of the Rebellion R2----- Opening
Shiawase Neiro ----- Code Geass : Lelouch of the Rebellion R2 ----- Ending
Masquerade ----- Code Geass : Lelouch of the Rebellion ---- BGM
Sensibility---- Code Geass : Lelouch of the Rebellion ---- BGM
Continued Story ---- Code Geass : Lelouch of the Rebellion ---- BGM
Don't Say Lazy ----- K-ON! ----- Ending
Snow Fairy ----- Fairy Tail ----- Opening
Futatsu no Kodou to Akai Tsumi ----- Vampire Knight ----- Opening
Fight or Flight ----- Dragonaut ---- Ending(?) ( Can't remember :P )
Perfect Blue ----- Dragonaut ----- Opening
Treasure ----- Seitokai no Ichizon ----- Opening
Diamond Crevasse ( All varying versions )----- Macross Frontier ----- Ending / BGM
Iteza Gogo Kuji Don\'t be late ----- Macross Frontier ----- BGM
Scarlet ----- Karin ----- Opening
Free and Dream ----- Tears to Tiara ----- Opening
Blue Sky , True Sky ------- Tears to Tiara ----- Ending
The WorLd ---- Death Note ---- Opening
Ketsui no Asa ni ---- Brave Story Movie ---- Theme Song / Ending Theme
Kage Futatsu ---- Clannad ---- Not sure :P
Megumeru ----- Clannad ---- Opening
Tori no Uta ---- AIR ---- Opening
Last Regrets ----- Kanon Remake ---- Not sure...was it the Opening?
With You ---- InuYasha The Final Act ---- Opening ( I like most of InuYasha's music but...it's a too much to write :P )
Weeping Alone ------ Tears to Tiara ------ Ending
Hishoku no Sora ----- Shakugan no Shana ----- Opening
Blaze ----- Shakugan no Shana ----- Opening
Joint ---- Shakugan no Shana ----- Opening
Prophecy ---- Shakugan no Shana S ----- Opening
Innocence ----- Shakugan no Shana S ---- Ending
Tenjou wo Kakeru Monotachi ----- Shakugan no Shana : The Movie ---- Ending
Akai Namida ----- Shakugan no Shana : The Movie ----- BGM
You ------ Shuffle! ------ Opening
Style ----- Soul Eater ----- Ending
Pre-Parade ----- Toradora ----- Opening
Orange ----- Toradora ----- Ending
Vanilla Salt ------ Toradora ------ Ending
Silky Heart ----- Toradora ---- I don't remember!
Holy Night ----- Toradora ----- BGM / Ending
Kurenai ----- Night Wizard ---- Opening
Princess Primp! ----- Princess Lover ---- Opening
S.S.D ----- Princess Lover ----- Ending
Usotsuki ---- School Days ----- Ending
Be your girl ---- Elfen Lied ---- Ending
F.D.D ---- Chaos ; Head ---- Opening
Super Special ----- Chaos ; Head ---- Ending
Gorgeous 4U ----- Special A ----- Opening
The Fine Every Day ----- Kiss on My Deity ---- Opening
Anata ga Ita Mori ---- Fate / Stay Night ---- I honestly don't remember ....I think it's the Ending?
Hikari ---- Fate / Stay Night ----- Ending
Kimi to no Ashida ( Note that I changed the "ta" to "da" for cencor purposes ) ---- Fate / Stay Night ---- Not sure :P
Imitation ---- Fate / Stay Night Movie ---- Theme Song
Happy Material ( All versions of it ) ---- Mahou Sensei Negima! ---- Opening
Most of them are written via memory and notes.... I think I might've missed something so I'll update this if something comes up.