Those zalman fanmates are another good option but you still need to have one motherboard header per fan you're using with the fanmate (since the fanmates run inline to your motherboards fan headers).
If you're going to go with trodas' suggestion I would add this little note... Label The Modded Connectors!!

I've seen a few cases where a customer has come in with a burnt/not working hard drive or optical drive and tells me that the previous owner of the system had no problems with it..... So please be sure to label any modded connectors on your power supply for your own, and everyone else's, benefit! Also, if you're unsure of your soldering / heatshinking abilties get someone with experience to do it because a bad solder joint can fail and bad shrinkwrapping jobs can cause the exposed wires to short out on the chassis

.
Good luck with your project!