Almost everything is on you tube 4 u to check out!!! This is a very useful activity if you want to focus on pronunciation , rhythm and ultimately speed.
Remember you have these rhymes printed out. A good exercise progression could be identifying sound patterns such as rhyme and vowel repetition. Then, you can proceed to say the patterns aloud following the artist's flow. Finally, you can start learning some lines by heart parroting pronunciation and rhythm. Once you know a good old chunk you can use it as a kind of mantra to warm your tongue up to prepare for some real English.
Wu banga 101 by Ghostface Killah
http://youtube.com/watch?v=4HD1KykTG2o
Lalala by Saul Williams
http://youtube.com/watch?v=yaFhd_xYz0o&feature=related
Underground by KRS-One
http://youtube.com/watch?v=dQ6hJdYk15A