This is my new series to keep us perpetual nerds up-to-date on trendy things.
Mixing two songs to make a new one. This one is not only popular, but there are amazing music videos mashed up to make something that takes music from kind of 2D to 3D. Often, they take two bands that are completely unrelated and once mashed up, they actually make sense together!
(two of my favorite bands, Black-eyed Peas and Kings of Leon)
I get my fix every day on my favorite mashup blog, Mash It Up - The Music.