Since the last one seems to have gone AWOL, it's time for that forum favourite: lists!
I have a copy of an old list so we have a starting point. No need to quote the entire list, since I'll update the one below. Just add your username, format and gamertag.
If there's a problem/error/change in your gamertag details or username, please let me know and I'll edit the list.
XBL
===============
Alexander - monko87
Ash3000k - DarkDreamer3000
Beddie - Beddie07
Bennylenny88 - Bennylenny88
boxxer1973 - fatron7
chip20 - chip20
craigy123 - toeshooter86
d0mokun - d0mokun
D4rk1 - HKM UK
Danny08Gti - Dannywilson913
Dave789 - Sharpie
Deako - Deako80
del boy - Royal T 666
DJM - davem01
DomT - BigBadDom
eyebrows - pauleyebrows1
Garth - Garthy XXX
GINGER224 - RJHRULES
graeme - Internet server
Gtiain - h1nch84
GTiBEER - Logo Lips
holepunch - Holpunch2
JackG - jacksbad
jt1 - dubjt
johnhol78 - johnhol78
JoeDarKa - JoeDarKa
joesgti - JOE1203
JPC - j88ypc
Jules86 - Jules S3
Jussa - Jussa
keano - Keanobeano
keV_vaux - kevbradford
ktlstar - Bananaman Eric
Lew 91 - Vaniize
mad_pete - Moses2015
marty341 - M4RTY F4RTY 341
Maverickfsi - Maverick_11-G60
Mertyvw - MertyDelight
micaerin - mimgadget
MitchGTI - M1tch f
monte - Monte1975
Nasir - nas890786
nezquick - nezquick
Nickyboy - NickCTR
Nodz - Nodz86
Pauli - Poleykan
phil197 - Phil197
Poverty - Ldnjason
prepree - Pre pree
R444WRR - mrdmh
RagingKileak - raginkileak
RobH - Rob4123
S2 Ant - Lagerstars
Saint Steve - Saintsteve330
scotta - cuprascott
Screech89 - Screech89
SL03 JOE - EnZyme GFX
Smudgster - fcsmudge
SteveyD - SteveyD 81
Syrag64 - Syrag64
Thor - Northern Thor
vwrascal - vwrascal
WolverineMAc - Wolverinemac
WhiteGTI - R77CHRIS
WhiteHartMart - WhiteHartMart
wisebuddah - wisebuddah
PSN
================
Ash3000k - Dark_Matter3000
B3n - St7ckz
BUDGIESTONGUE - BUDGIESTONGUE
CupraK1 - Cupra300bhp
CupraKris - Burt07
Dannyboy88 - DSW_88
delboy - Royal_T_2010
dirrty-derv - MIKEROWELLY
DJM - davem01
edd666999 - edd666999
Garth - gdude101
golf nutter - REM_fan_UK
Gti_Mad - BROWZA_TW14
gtipirelli - daytonapirelli
h4rdy - H44RDY
holepunch - Holpunch2
Huggers - Huggers
jhtrophy - jhr26
JLCoad - coad1984
JPC - J8YPC
JoeDarKa - JoeDarKa
jrstevo - Angry Jimm
Jules86 - Schmint
K1Shane - K1Shane
kong86 - ldn2612
Little_Dave - G5_D4V3
Lone_Par - Lone_Par
marko - markobucko
MC71 - mcaborn
micaerin - micaerin
Mikeygtir - mikeygtir
MJR - MarkJohnston2012
muchgti - much786
nathangallo - Njgallo
neg - snezza78
Nodz - Nodz86
PaulR32 - Roadster18
paulw123 - paulw123
Phil Miller - Phil miller
RagingKileak - raginkileak
richwig83 - richwig83
RobH - RobH4123
Sharman - old-volks
SL03 JOE - Enzyme_Xi
Smudgster - evileagle
stealthwolf - cloakedwolf
tmagnet - magnet120
Vtec Abuser - VtecAbuser
vwrascal - vwrascal
Welshman Adam - Frank1e
WhiteHartMart - WhiteHartMart
wisebuddah - tenderoni
xjscx - xjscx
yetidom - yetidom
Steam
===============
edd666999 - edd666999