It's been around a couple of years but a friend showed up at a ride this spring with a little 3" x 3" player tucked in his shirt pocket, all excited about his new find he gave us a update on what he found. Sony primarily, but others do make them has a Mini Disk player that uses a new compression technology that allows you to put 5 full CDs on one little 2" x 2" 80 min. Disk with fantastic Quality. These units are water resistant and come with remotes that you can clip to the outside of your jacket allowing track & volume control all for under $150.00
I know this sounds like a sales pitch but these things are so neat I just had to share. You can check the specs. out at Sony's Site. but the real deals are on EBay at Sony MD