Are there any TLD registrars that support dnscurve?
To get DNSCurve working you need two things:
For #1, see Ronald's answer.
For #2, your options are very limited. I presume that DJB's own software supports it, but I'm not aware of any others. In any event DNSCurve only protects the path between a recursive resolver and the authoritative server - it does nothing for the communication between stub resolvers and recursive servers.
3 different registars were used: register.com, godaddy.com, and networksolutions.com. All of them accepted and published DNSCurve nameserver names correctly. In the overall, register.com was the easiest one to work with for someone who wants to manually configure custom nameserver hostnames and IPv4 glue.
So, let you register nameservers for your domain with dnscurve names, any should work, but I don't know that any root server supports it, or will support it, any time soon. If they do, expect a minor one to, not .com or the like.