I want my users to use their own domainname and I want them just to point their domainname to my *namerservers*. But I don't want to run them by myself, I am looking for DNS provider where I can get DNS services with a customizable name for the nameservers and an API to set the records (and if possible running on Linux/Unix, and with servers at several countries and competitive prices)

Anybdody has some recommendation for me ?

thanks in advance
Roberto

enom has this but you have to use their dns*.name-services.com