Here's some Dead Prez lyrics, examples of socially conscious rap music:
http://www.lyricsfreak.com/d/dead+pr..._20038331.html
http://www.lyricsfreak.com/d/dead+pr..._20038336.html
http://www.lyricsfreak.com/d/dead+pr..._20326581.html
http://www.lyricsfreak.com/d/dead+pr..._20038334.html
http://www.lyricsfreak.com/d/dead+pr..._20038327.html
I have never heard this group on the radio, because the media doesn't want that image. There's other good artists too, like Common,Talib Kweli, BlackStar, Afu-Ra, KRS-One, The Roots, De La Soul...So rap music is NOT all about gangbanging, bling, and bitches.