Holy crap- I was looking for a specific mashup of a Jay-Z song, and I just happened to find the mother lode of hip hop mashups by Duncan Gerow on Soundcloud. There are 225 tracks in his playlist, listed alphabetically by artist, and he includes everything from Aaliyah and Fabolous to Childish Gambino and Kendrick Lamar. He has a ton of other great stuff on his page too. I could listen all day. Definitely worth checking out and downloading.