LOL... just trying to imagine the big and bulky Studio 20 tied up to my arm... I'd bet that heavy thing is gonna rip my arm right off. Maybe you could use some sticky tape?
Now seriously, do you still have that blue pocket it came with? It's got that ear on the back. All you'd need is some sort of belt.
Dunno if this leather case:
http://www.newmp3technology.com/proddetail.php?prod=studiocase&cat=5has a clip attached on the back.
But other than that.... I dunno of any "armband" for the studio...
Maybe some of this will do:
Ipod storeJust noticed that this might be compatible with a studio20 since it works with the first generation Ipod... the Studio is a bit thicker though...
ClickJust look for other brands than archos as well... the iRivers might be about the same size.
martin