Codes will be posted here, after you post your code and it is put into this list your post will be deleted for space and what, thank you.
Mario Kart DS codes:

451031097155 - Sailorcancer2004
279232406148 - Aloiv
347951807670 - Ness10 (known as Ness on the tracks)
429556198596 - gcnplayer5 (known as ndsfreak on the tracks)
506865783993 - blinx000 ( known as Aivan on the tracks)
287822450134 - Funky Monkey Bill (known as <-SiKo-> on the tracks)
141793377142 - memic
004354548149 - soramaster3 (known as sora on the tracks)
455326225163 - altoid_masta (known as altoid1 on the tracks)
068778948900 - Dark Ramirez
463915988006 - N t e r
446736138464 - henaro
189038123011 - ayukichan (known as CATS6484 on the tracks)
201923090615 - iProd (known as iProd on the tracks, who knew?)
455326225679 - mavrick_hunter (known as Soulhunter on the tracks)
030124405166 - gamer712
176153249244 - Zibeto
150383490318 - Scareg (his REAL code, known as scareg on the tracks)
180448350331 - a'dieu (known as a'dieu on the tracks, who knew?)
193333108285 - matt2004 (known as santa on the tracks)
055894295793 - blessed demon (known as Geebus on the tracks)
541225460059 - jeffsbud
360836823686 - felix45 (known as felix45 on the tracks, and owns!)
150383497190 - Platformer Adept
420966269706 - Kaluvien (known as Blk Mage on the tracks)
296412221784 - SolarShadow (known as Varron on the tracks)
021534307235 - razorrush (known as razorrush on the tracks, who knew?)
201923391131 - Girl_lover5 (known as TimeKing on the tracks)
326477104960 - Shawnzy34
236282652639 - Neo_Falco (known as NeoFalco on the tracks)

Tony Hawk's American Sk8land codes:

292118269532 - altoid_masta (also known as altoid1)

Animal Crossing: Wild World codes:

dsprox- 5412-2655-3563, dan, penway
memic- 1374-9962-7065, MEMiC, Plymoth
FireBlix- 4209 6747 7581, Phoenix
Ness10- 1117-2982-4712, Ness, Portland
BlueRockman- 4037-8759-6342, Mike, Twoson
felix45- 0516-0029-6428, Kroger