I normally don't listen to rap or hip hop--in fact, most of it I typically detest--but there have been some songs and artists that have really caught my attention.
I like most of Eminem's stuff, especially when he collaborates with Dre. That Dre CD almost made me want to listen to the genre more often but I heard enough of it when I played basketball in high school.

Those Jay-Z mashes with Linkin Park were decent, especially the one with Numb.
I don't really have anything to add to the original post, but if you like hip hop satire, the Ali G show is awesome. That character is superior to Borat in just about every way.