illmatic- nas
black on both sides- mos def
lifestlyez of tha poor and dangerous- big l
the infamous- mobb deep
midnight marauders- tribe called quest
Blueprint 2- Jay-z

Common- Resurrection
Dr. Octagon- Dr. Octagonecologyst
The Roots- Game Theory
Deltron 3030
Mos Def- Black on both Sides
Mos Def and Talib Kweli are Black Star
A Tribe Called Quest- Midnight Marauders
I know it's more of a mixtape but Talib Kweli's collaboration with Madlib- Liberation

Wu-Tang Clan - Enter the Wu-Tang (36 Chambers)
People Under the Stairs - Fun DMC
De La Soul - 3 Feet High and Rising
Public Enemy - Fear Of A Black Planet
A Tribe Called Quest - Low End Theory
The Roots - Phrenology
Mos Def - Black On Both Sides
Aceyalone - All Balls Don't Bounce
Black Star - Mos Def & Talib Kweli Are Black Star
Gang Starr - Step in the Arena
Notorious B.I.G - Ready to Die
2Pac - Me Against the World
Ugly Duckling - Bang for the Buck

I will have to end there, already feel a huge amount of crippling guilt at the ones not mentioned.

in no particular order:-

A Tribe Called Quest - The Low-End Theory
Ghostface Killah - Ironman
Jay-z - The Blueprint 2 : The Gift and The Curse
Snoop Dogg - Doggystyle
Ice Cube - AmeriKKKa's Most Wanted
N.W.A. - Straight Outta Compton
2Pac - Me Against the World
Public Enemy - It Takes a Nation of Millions to Hold us Back
El-P - I'll Sleep When You're Dead
Eminem - The Marshall Mathers LP
Wu Tang Clan - Iron Flag

Mos Def - Black On Both Sides
Themselves - Them
Busdriver - Temporary Forever
cLOUDDEAD - Ten
13 & God - 13 & God
Immortal Technique - Revolutionary, Vol. 1
Wu Tang Clan - Enter the Wu Tang
A Tribe Called Quest - Midnight Marauders
Black Star - Mos Def & Talib Kweli Are Black Star
Atmosphere - Leak At Will
Eyedea - The Many Faces of Oliver Hart or How Eye One the Write Too Think
Celph Titled - The Gatalog: A Collection Of Chaos
Doseone - Skeleton Repelent
Boom Bip & Doseone - Circle

Public Enemy - It Takes A Nation Of Millions To Hold Us Back
Beastie Boys - Paul's Boutique
Public Enemy - Fear of a Black Planet
A Tribe Called Quest - The Low End Theory
De La Soul - 3 Feet High And Rising
N.W.A - Straight Outta Compton

I haven't listened to enough rap beyond the golden age stuff.

also:-

Nas - Street's Disciples
Beastie Boys - Paul's Boutique

No special order...

Check Your Head- Beastie Boys
Brotherhood of the Bomb- Techno Animal
Absence- Dalek
Fear of a Black Planet- Public Enemy (I'm seeing more of 'It Takes a Nation'... interesting)
Company Flow- Funcrusher Plus
Phrentology- The Roots
I'll Sleep When You're Dead- El-P
Saul Williams- Saul Williams

haven't heard it yet

Mobb Deep - The Infamous
Pac - All Eyez on Me
Wu Tang - Enter the 36 Chambers
NWA - Straight Outta Compton
DMX - It's Dark and Hell Is Hot
Gza - Liquid Swords
Dre - The Chronic
Nas - It Was Written
Nas - Illmatic
Big Pun - Capital Punishment
B.I.G. - Ready to Die
Eminem - Marshall Mathers LP
A Tribe Called Quest - Low End Theory