This is not an original idea.
But this instructable shows you how simple it is to create helmet speakers on the cheap :)
What you'll need are:
1. Old Headphones - NOT earphones, those are too small, computer headphones have at least a 1W speaker inside them
2. iPod - the best for this would be the shuffle, the one with tactile controls and also the smallest
4. Wires - you can just use the wires from the headphones, that's what I did
5. Soldering skills
Step 1: What You Need
Dig through your stuff and you'll probably find some old headphones, I found some computer headphones that I got as a freebie when I bought a PC desktop, if you don't have any, just buy some, they are quite cheap. I also found an old iPod shuffle, the 2GB memory would give me about 3 hours of music which is great! Of course you'll be needing a helmet to put it on as well :)
Step 2: Gut the Headphones and Get the Speakers
Next would be to strip the headphone speakers out of the headphones, try to retain the foam, you'll be reusing them later
Step 3: Reconstruct the Wiring
When you cut the wires, just remember which is attached to which, so you'll be able to solder them back and music will actually come out, I reused some of the plastic casing of the headphones to use as a case for the speakers and I also reused the foam to cover everything. Stick some Velcro (the hook part) on the speakers. I also reused the mini-jack and the wires from the headphone (ok so pink isn't really a masculine color for the jack but hey! it's free :) )
Step 4: Place the Speakers
In motorcycle helmets, there's always a small space in the cheekpads, that's your sweet spot, position the speakers there so as not to interfere and become uncomfortable during use.
UPDATE: after a while, I inserted the speakers into the cheekpad to make it more permanent.
Also run the wires around the back and INSIDE of the helmet lining, always good to put some slack to prevent the wires being pulled for any reason
Step 5: Position the Player
After that, just position the iPod outside the helmet, I opted to place in near the cheek so that I'll be easir to adjust volume, fast forward to the next song etc. Plus since it's almost in front of the helmet, there's no chance of anyone swiping it.
Use Velcro to stick the iPod on the helmet, just remember to use the eye part (the smooth side) on the iPod, that way, if you remove the iPod from your helmet and put it in your pocket, it won't snag on the inside of the pocket.
It's a good idea to remove the player when leaving your helmet on your bike when you park, and just tuck in the jack inside.
That's it, crank up the volume and enjoy your tunes!
The good thing about this is when you park and remove your helmet, you don't have to fuss about removing anything since everything is self-contained on the helmet, just remove it and go!
Since the iPod is placed upside down, rain drizzle can't really affect it but nevertheless remove it when it does rain just to be safe :)
Friendly reminder, don't crank up the volume too much and remember to be a responsible rider, happy trails!