I find this one incredibly cheap (15$): NetDisk ENCL-1P 3.5" USB 2.0/RJ-45 Ethernet NAS External IDE HDD Enclosure
I've found it on Amazon too, with reviews that may help determine how it works or if it could be OPL compatible.
Do you think it can work with OPL? It says "Ximeta NDAS 2011 chipset", if that can help somehow.
EDIT: Forget it, I've read it's IP-less and needs drivers on every computer you connect it... So I guess that makes it not compatible with OPL.
EDIT 2: I found this on the website of the manufacturer (Ximeta, under "Markets and applications/NDAS applications"):
Found more info (quite old, from 2002!) about the BroadQ thing hereQuote:
-Sony's PlayStation 2 is another example to demonstrate the application and flexibility of NDAS technology
-XIMETA's partner, BroadQ developed a title CD which turns Sony PlayStation 2 into a network multimedia player.
-Install the software to allow Sony PlayStation 2 to retrieve multimedia files (photos, music, movies) stored in NDAS storage and play them directly to your TV.
Maybe there's is way to make it work with OPL, could be a great solution (because it is really cheap and small) for those who can't put an old computer with FreeNAS on the family living room...