All,
Thanks to everyone who replied. Several people asked that I post some of the suggestions that I received to NANOG, so here goes. 
Lucent QIP <http://qip.lucent.com>
Granite Systems <http://www.granite.com>
Nets <http://www.open.com.au/nets>
Checkpoint MetaIP <http://www.checkpoint.com/products/metaip/>
Tree ftp://ftp.tic.com/pub/tree/tree-0.0.1.tar.gz
LanDB <http://avenir.dhs.org/landb/>
Several people also replied that they are building their own database using either plain-text records or SQL databases (mySQL, PostgreSQL, mSQL, etc).
I have personally looked at Tree and got a demo copy of Lucent QIP (No Windows 2000 server setup yet to test ). While testing tree, I found documentation and some of the more advanced “features” (e.g. email alerts, permission levels) were lacking.
On the flip side, QIP and MetaIP have the ability to manage your DNS and DHCP services. While that is nice, I really don’t need the functionality and it does drive the price higher. 
I would suggest trying out the above software. However, if they do not fit your needs, it looks like you have to build your own.