J-M

Jean Michel Jarre - Oxygene (maybe Chronologie)
Judas Priest - Painkiller
Norah Jones - Feels Like Home

Beverley Knight - Affirmations
Diana Krall - The Girl In The Other Room
Kyuss - Sky Valley
Kiss
Kittie - Spit

Ladysmith Black Mambazo
Linkin Park - Live In Texas
Led Zeppelin - 4 symbols
Louise
L7 - Bricks Are Heavy

The Music
Madness - Divine
Megadeth - Countdown to Extinction
Metallica - (Load/RELoad & St. Anger don't count...aren't up to standard) Master of Puppets
Machine Head
Brian May - Back to the Light

Madonna
Alanis Morrisette - So-Called Chaos
Massive Attack - Mezzanine
Martina McBride
Reba McEntire
The Montrose Avenue

Kirsty MacColl
Michael McDonald
Katie Melua
Jane Monheit
Mudvayne - L.D. 50

To consider:

Mushroomhead
Mortis (I can't remember how to spell this band...sorry)