Because the last version of Billy (and only a beta) is already a year old I just tried 1by1
. For its small size (~100 kb) it's great (it even has an audio enhancer that works wonders on some bad recording I just tested it on), and it seems you can just 'install' it (by just copying the folder) several times (naming the folder differently) to use several instances of it. The "remembers last track and position" comes in handy there, looks like this will become another player I'm regularly using next to xmplay, Trout and mp3DirectCut!
Edit: Haha, I just found out that mp3DirectCut and 1by1 are from the same guy!
Now I remember reading about 1by1 before (when checking out mp3DirectCut and suggesting features/reporting bugs, but never had a closer look)...