The battle raps at the 8 Mile are an entire sequence of pwnage moments served up by B. Rabbit (played by Eminem). His final battle rap against Papa Doc is one of the most glorious moments of pwnage ever on the big screen and is too long to post here, but I'll repost what I thought was the best few lines.
B. Rabbit: But I know something about you. You went to Cranbrook, that's a private school! What's the matter dawg, You embarrassed? This guy a gangsta? His real name is Clarence!
"Fuck the beat! I'll do this acapella!"
"And fuck this battle, I don't wanna win, I'm outty. Here, tell these people something they don't know about me." (throws him the mic). Indeed, that last battle was pure awesomeness.
What could possibly top Rabbit's last rap battle? Not much, but the entire crowd unanimously taunting Papa Doc into submission comes darn close. The look on Papa Doc's face is priceless as he surveys the crowd, and he realizes nothing he can say will impress these people. This is especially poignant as Rabbit went through this himself a week ago, and he actually choked while Papa Doc forfeited.
Of course, this ties in with just how clever Rabbit was during his rap. By starting it off as a Take That Me rap, he stole the best material that Papa Doc could've used.
Rabbit's battle against Lyckety Splyt was awesome primarily for being a turning point. Rabbit starts slow but builds it into a crushing display of his superior skill, culminating in his "split-lickety" line. The crowd clearly goes from hating him and laughing him off to cheering in amazement.
For this troper, the moment of Awesome came when B Rabbit won the battle...and then went back to work.
The last battle was undeniably awesome. However, it's a smaller crowning moment of awesome when his mother comes home - arms full of groceries - and offers to cook him dinner. Rabbit is (understandably) puzzled; then she reveals that they aren't being evicted. Why? She did go to Bingo; and won!
Don't forget earlier when Rabbit (Whom up to this point is shown as very shy and lacking in confidence) lays out a rap moment of pure awesome to a coworker making sexist and homophobic remarks to his coworkers and overall being an ass. Rabbit completely tears him apart and we get the first look at what Karma is going to bite Papa Doc in the ass.