Using earphones is bad because you can't hear anything around you
With some ext. speakers, you can still hear that Hybrid sneaking up on you! (most of the time)
This isn't an excuse for knowing whats going on around you while biking, or not having a rear-view mirror.
Edit [May 2013] - This instructable was created while I was still in middle school. I'm absolutely shocked by how much use it has received while my account lay dormant. Thank you for looking this through, and I may yet update it in the future so let me know what you think.
Step 1: Get The Materials
The speakers I'm working with in this Instructible are simple, non-amplifying speakers. They plug directly into a headphone jack and nothing else.
My speakers aren't very loud, that's why I'm putting them on the helmet and not the bike.
Make sure that the cord for the speakers is long enough to reach from your head to wherever you want to put the music player. If it isn't either readjust or hit a local radio-shack and get a small extension.
If you decide to use speakers that need to plug into an outlet, have fun and let me know how that turns out. (No, really)
I also used a helmet, iPod, plenty of hot glue, rubber bands, Popsicle sticks (Jumbo kind)
and oh, yeah, a bike.