Just listening to some Slick Rick and remembering how much Em was influenced and the homages he's paid to him throughout his career, how many other times his paid homage to others.
The list I have so far:
Slick Rick
-First verse of Canibitch, referncing Rick's classic Children's Story
-"We need bullets, hurry up run" from Bad Guys Always Die is from the same song.
-Part of the Shit Can Happen chorus is also from Children's Story
-"Rock the mic, RIGHT"
Rakim
-The columbine reference bit in I'm Back is taken from My Melody.
-Also from I'm Back the "Back is the incredible"
-The Way I Am's chorus is slightly taken from As the Rhyme Goes On
-Love/evol thing in Space Bound is a classic Rakim line from Man Above
Nas
-Uses the Ether chorus flow on Say My Name
Masta Ace
-Dunno whether this is intentional but on You're Never Over he spells out the word "over", just like Ace on Dear Diary
2Pac
-Obviously on Quitter and Hail Mary Remix he uses Pac's flow and rhyme scheme as a tribute
Method Man
Uses the "I'll fucking put your nuts on a dresser" thing from 'Method Man' on 36 Chambers in some freestyle.
Guru
Might be unitentional but:
Guru on Rite Where You Stand:
Your girl want me cuz I do it BETTER than you
Eminem on Seduction
Your girl on my dick cuz I spit it BETTER than you
Jay-Z
Jay-Z on Izzo - "Cant leave rap alone, the game needs me" is used by Em on Business.
I know theres loads more (I'm sure theres a load of Redman ones, some Tribe Called Quest ones and more Slick Rick ones) but I cant be bothered to think so you lot can post 'em.