Night Ripper, by Girl Talk, is one of the best albums I've come across in a long, long time. Girl Talk is Gregg Gillis, a white boy sample artist who works in biomedical engineering by day and creates wonderfully chaotic mash-ups of Top 40 songs by night. But these aren't mash-ups as you know them, they're dozens of songs all pasted across each other, grunge backing up hip-hop supporting spoken word. The results are perfect.
Relatedly, I've been using Emusic lately, and loving it. Knowing that my 65 downloads will expire actually forces me to seek out new music every month, and the result has been a slew of great discoveries and terrific sounds. If you've been considering taking the leap, join, and use me as your reference.