Public domain icons

I'm writing an RDF linter/visualiser and need some icons, preferably
public domain. I've been using Tango, but they don't cover all the
concepts I need. I want a coherent icon set covering the following:

   - Person
   - Organisation
   - Group (of people)
   - Document
   - Project
   - Book
   - Video/Film
   - Song
   - Album
   - Event
   - Place
   - Review
   - Other/Generic
   - Unknown

Anyone have any pointers?

-- 
Toby A Inkster
<mailto:mail@tobyinkster.co.uk>
<http://tobyinkster.co.uk>