Free IP address management software
Solution 1:
I'm currently using ipplan in production where I work and I'm quite happy with it. However do note that it doesn't support ipv6 and will require a complete rewrite for it to do so.
I have yet to find an ip address management project that will handle ipv6 well. That NOC project looks promising though.
Solution 2:
I tried PHP-IP, it's a webapp with a MySQL backend. But its currently v4-only. Another tool I use is RackTables. It's not just an IPAM tool, rather a rack manager, where your can document your devices, store config details and so on.