Looks pretty good, though I would probably want a non-free option if I was going to use it for a larger site, and maybe a few more servers around the world for better response times.<p>"Cloud DNS" is currently dominated by huge companies charging way more than they need to (Dyn etc.), with a few additions (location based response, better API, stats etc.) it has the potential to go somewhere, if that's what you want it to do.<p>Possible bug; the 'Log Out' link takes me to a 404 page - <a href="http://entrydns.net/users/sign_out" rel="nofollow">http://entrydns.net/users/sign_out</a>
One possible thing you might want to look into is Anycasting your DNS servers, although understandably this is costly. I myself was researching starting a DNS provider after Dyn bought EveryDNS, however the inability for me to find a way to cost-effectively provide Anycast was what stopped me in my tracks.<p>What you have right now looks good, good luck.