You didn't mention what OS....so I'll try to cover different ones:
One option -
Webmin.
It's a web-based interface for system administration - good point: it's free. Whether it will be what you want I'm not sure. I only know about it because there was one person asking for help in administration of DNS utilizing it
Matt's webmin problems.
If you are looking to pay some $$$...
DNS Boss
For NT or 2000 - DeEnesse DNS
Just do a search on Google for DNS GUI administration and you should find lots of choices. I've been fortunate that I can still use CVS and vi for the sites I have to admin.