Sean Alexander had a link to WMP Mixer Friday. This is a cool app that lets you have two media streams and mix between them DJ style.
I used to DJ back in college for the campus radio station. We had a remote kit so we could spin tunes for frat parties. Typically, my job at these remotes was to lug heavy DJ equipment, but I did occasionally spin at parties. The one thing WMP Mixer is missing is the ability to preview the next song while the current song is playing. Of course, you’d need more than the standard single audio out that most PCs have these days. I have a 5.1 sound card that I bought for my Media Center and haven’t installed. I wonder if you could play media streams to separate channels (rear speakers could be used for preview). I’m curious if different instances of WMP will let you drive different sound card outputs. I’m guessing no, since I can’t seem to find an option to change the sound output of WMP.