Matchmaker, anime matchmaker...
Peacemaker Kurogane
HijikataxOkita (well, they ARE... erm, VERY gay for each other. :P)
Prince of Tennis
MomoshiroxAn
HanamuraxReiji
OishixEiji (again. incredibly GAY for each other)
Slam Dunk
AyakoxMiyagi
SakuragixHaruko.
Hajime no Ippo
KumixIppo.
Eyeshield 21
HirumaxMamori.
One Piece
LuffyxNami
ZoroxTashigi.
Mazinkaiser
KojixSayaka.
Fire Emblem: Rekka no Ken
GuyxPriscilla
LynxHector
DartxFarina.
Fire Emblem: Fuuin no Tsurugi
DieckxThany
TatexKlein
ClarinexRutger
RoyxSophia
Fire Emblem: Seima no Souseki
EphraimxTana
EirikaxForde
SethxNatasha
KnollxNatasha
InnesxL'Arachel
RossxAmelia
Guilty Gear
SlayerxSharon
KyxJam
DizzyxTestament.
King of Fighters
KyoxYuki
KyoxChizuru
K'xKula
AlbaxLuise.
Captain Tsubasa
HyugaxMaki
MatsuyamaxYoshiko.
Gundam SEED/SEED: Destiny
ShinnxLunamaria
KiraxLacus.
Bleach
MatsumotoxIchimaru
YoruichixSoifon
HitsugayaxHinamori
RenjixRukia
IchigoxOrihimexTatsuki
Fruits Basket
HatorixKana
TohruxYuki
KyoxKagura
Naruto
NarutoxHinata
LeexSakura
ShikamaruxTemari
Basilisk: Koga Ninpu Chuu
YashamaruxHotarubi
AkeginuxKoushirou
Cowboy Bebop
SpikexJulia
Pokemon
MayxDrew
AshxMacey
TraceyxDaisy
JessiexJames (PLZ keep them IC!)
Code Geass
SuzakuxEuphie
MillyxLelouch
KaguyaxLelouchxKallen
Jeremiah/Sayoko
Axis Powers Hetalia
Prussia/Hungary
Ukraine/Russia/Belarus (yes, incest. STFU, it's funny)
Sweden/Finland (CANON, so yeah)
France/Seychelles