Florian Soenens has released a beta of IconBox 2, an update of its icon organizer for Mac OS X. You can sign up to participate at http://www.iconboxapp.com .
In version 2, you can create and manage new boxes, with unlimited nesting capabilities of sub boxes. You can also create new smart boxes designed specifically to recognize different icon types.
IconBox 2 also offers real time search capabilities and more. Just remember: beta software is unfinished software so use with care.