I can't be bothered to do mine right no, so this may be somewhat hypocritical, but here's a little game...give your favourite band beginning with each letter of the alphabet?

a perfect circle
blind guardian
c dunno
devin townsend band / depeche mode
fear factory/fates warning
garbage
helloween
iced earth
j dunno
kreator
lacuna coil
ministry
nine inch nails (pre fragile anyways)
opeth
porcupine tree
queens of the stone ages
rhapsody
smashing pumpkins (i only know one SYl album as of now, soon to change)
tool
u dunno
VAST
w xyz dunno

off the top of my head, without much thinking

Akercocke or Atomic Ants (aarght it starts here already)
Bloodbath
Chimaira
Devin Townsend (Band)
Exodus
Foo Fighters
G I'll have a 50:50
Hatebreed
In Flames
Jamiroquai
K Can I call a Friend?
Left
Muse
Non-Human Level
Opeth
Pain of Salvation
Queens of the Stone Age
Reinhardt (Django)
Strapping Young Lad
Tenaious D
U I'll ask the audience
V Now I'm busted...
Williams (John)
Xasthur (just proud that I know one)
Yattering
Zimmers Hole

apocalliptica
berzerker
cannibal corpse
dtb
enigma
fear factory
graveworm
hypocrisy
impelliteri
judas priest
kid rock (stop laughing!)
lacuna coil
mushroomhead
nightwish
opeth
porcupine tree
queen adreena
rob zombie
syl
tool
unit 187
vnv nation
white zombie
xentrix
yattering
zimmers hole

phew that was hard.

A Atheist
B Buckethead
C Cynic
D Dysrhythmia
E Ephel Duath
F Frantic Bleep
G Gordian Knot
H Allan Holdsworth
I Illogicist
J Ron Jarzombek
K Kayo Dot
L Linear Sphere
M Meshuggah
N Necrophagist
O Opeth
P Pain of Salvation
Q Quo Vadis
R Having a mental block
S Spiral Architect
T Devin Townsend (and DTB band)
U Ulver
V Vuvr
W Watchtower
X Don't think I like any
Y None I listen to regularly
Z Zimmer's Hole

ahh can't think

Arcturus Agalloch
Bob Dylan
C... Gonna have to go with Count Basie I guess. Or Cypress Hill
DTB/Dillinger Escape Plan
Ephel Duath
F... Oh god, I'm not doing this letter. Frank Zappa, Faith No More, Fantomas, Fredrik Thordendal, etc etc. There's just so much.
Genesis
Henrique Annes
Iced Earth
John Coltrane/John Zorn
King Crimson
Lovage
Meshuggah/Mr Bungle
Neurosis
Orphaned Land
Peter Gabriel
Queensryche
Rush
S... another difficult one. I'll go with Strapping Young Lad
Tori Amos
Ulver
Voivod
Wynton Marsalis/Within Temptation
X...blah i dont know... (general patton vs the) X-ecutioners?
Yeah I got nothing
Zip zap zop nothing here either

A Arch Enemy / Amon Amarth
B Blind Guardian
C Children of Bodom
D Devin Townsend / Dream Theater
E eXodus
F Fear Factory
G Genesis (the old ones)
H Haggard
I In Extremo / In Flames (Jester Race and Whoracle)
J J.B.O / Judas Priest
K Kamelot
L Liquid Tension Experiment (maybe)
M Mercenary
N Nevermore
O Opeth / Orphaned Land
P Porcupine Tree
Q Queen
R Rhapsody (I love this cheesy melodic metal)
S Soilwork / Symphony X / SYL
T Turisas / The Flower Kings / Transatlantic
U U2 (I like some of the older songs)
V Van Halen
W Within Temptation (just kidding)
X Are there any good bands starting with X?
Y Yes (not regulary)
Z Zimmers Hole

Agalloch/Anathema
Bal-Sagoth
Cradle of Filth
Devin Townsend (band)/Dream Theater/Dornenreich
Evergrey
Fate's Warning
Graveworm
Hypocrisy
Iced Earth
Joe Satriani (not a band, but...well)
Katatonia
Led Zeppelin
Metallica/My dying bride
Nevermore
Opeth/Orbital
Pain of Salvation/Pink Floyd/Portishead/Porcupine Tree
Queensryche
Red Hot Chili Peppers
Strapping Young Lad
Tristania
Ulver/Underworld
Vintersorg
Woods of Ypres
X,Y,Z - none

A Anathema
B Bloodbath
C Clutch
D Devin Townsend Band, The
E Emperor
F Fear Factory
G Gabriel, Peter
I Iron Maiden
J Jethro Tull
K Katatonia
L Led Zepplin
M Mastodon
N Nightwish
O Opeth
P Porcupine Tree
Q Queens Of The Stone Age
R Rammstein
S Strapping Young Lad
T Tool
U Ulver
V (i'll probably think of one later)
W Within Temptation
X (i dunno)
Y Yes
Z Zyklon

Arcturus
Black Sabbath
Carbon 12
Delerium
Emperor
Fear Factory
Garbage
Halford
Iron Maiden
Judas Priest
King Crimson
Led Zeppelin
Meshuggah
Nile
Opeth
Peccatum
Queen
Rotten Sound
Strapping Young Lad
The Devin Townsend Band
Ulver
Vader
Winds
Xorcist
Yob
Zyklon

[Blazingmonga]

Apocalyptica
Blackfield
Corrosion of Conformity
Devin Townsend Band (& Co.) or Dredg
Evenlight (Fuck Yeah!)
Faith No More
Garbage, Gojira, Girls Aloud?
Holst? I don't have many H's...
I don't have any I's at all! I smell!
Jamiroquai, Jefferson Airplane, Juno Reactor
Karma to Burn
Lovage
Meshuggah, Massive Attack, Monster Magnet
No Doubt, Non Human Level
Opeth
Porcupine Tree
Queen
Rammstein
SYL!!! Or also Soil or Soft Hearted Scientists
The Devin Townsend Band...!!! This list would be unfair with only one mention.
Ulver
Vast
What the heck begins with W? I need more W!
Xylophones are neat. Don't know about any bands though!
Zimmer's Hole, hands down.

Phew!

For now:

Arch Enemy (Pre Anthems..)
Bolt Thrower
Carcass
DTB
Edge of Sanity
Freak Kitchen
Gamma Ray
Hypocrisy
In Flames
Jerry Cantrell
Katatonia
Leatherwolf
Morbid Angel
Nocturnal Rites
Opeth
Project Hate, The
Quill, The
RHCP
SYL
Tiamat
Uriah Heep
V/W/X/Y no idea
Zimmers Hole

[djskrimp]

You people and your lists...

A=A Perfect Circle
B=Big Wreck
C=Cubic Space Division
D=Devin Townsend, et al
E=Eldritch
F=Faith No More
G=Gojira
H=Haunted
I=In Flames
J=Jesu
K=King's X
L=Living Colour
M=Meshugah
N=Nevermore
O=Ozzy Osbourne / Opeth (I ain't choosing one over the other)
P=Pantera
Q=Queensryche
R=Raunchy
S=Strapping Young Lad
T=Textures
U=Ulver
V=VAST
W=Winger (Bite me, Reb Beach is an awesome guitar player)
X=X-Japan
Y=Yes
Z=Zakk Wylde

I think I'm really gonna have to bend the rules on this one...

Antiproduct
Bob Mould
Clash
Dev!
Elvis Costello
Foo Fighters (the first two albums anyway)
Guitar Wolf
Honeycrack
Iron Maiden
Johnny Cash
Killing Joke
L Stuck!
Manic Street Preachers
Nelson, Willie (Told you I'd be pushing it! )
Oasis (Nobody take the piss!)
Paul Westerberg
Queen/QOTSA
Replacements
System of a Down/Skunk Anansie
Therapy?/Tom Waits/Tool
Urge Overkill
V Stuck again!
Wildhearts/Ween
X Stuck!
Yo-Yos
Zappa