So far, one of the better options I've seen for itx form factor combined with hot swap bays:
http://www.istarusa.com/en/istarusa/products.php?model=S-917
7 5.25 bays, so depending on hard drive size, 10-12 drives minimum.
http://www.istarusa.com/en/istarusa/products.php?model=S-917
7 5.25 bays, so depending on hard drive size, 10-12 drives minimum.