Most people would just use their phone but over the years I've concluded that using a phone is the worst thing for music playing or gaming, since it kills your battery and slows it down for the communication functions you need it for the most. That and its a pain to plug it in or remove the card thru a case to update its files.
If I have a game system with me, the one I'd have the easiest time copying music to is the one with the easiest removable media access, and the Mega Everdrive one is so very convenient, except for the need to have to convert the files.
When I travel to conventions, and retro gaming ones in particular, its fun to pack a portable game system with a video input to test all the crap I end up buying, and for gaming parties and the like. My Nomad is set up to do this, and having the ability to play a huge game library, and now music when I'm on the road is great! The li-ion batteries I use are cheap, very portable and last many hours. I'm all for adding of neat extra features that enhance the usage of our devices, even if they're for old beloved favorites. Besides, its just freakin' cool.

Still hoping for low bitrate DIVX/XVID playback in the future. XD