It’s cool to host a zone’s records here, or, if you like, a delegation to your DNS servers can be done.
All domain names are first-come, first-served. Current tildes get priority seating/reservation for the zones that match (ie, your.tilde, team.tilde, yourtilde.tilde, town.tilde, etc etc).
All .tilde DNS servers are listed on the NS List page. You should be able to pick any of them, and they will just work. These name servers will also resolve regular domain names, and opennic names, and are suitable as personal use DNS servers.
Current(ish) status of the the .tilde name servers can be found here: http://ubergeek.tildecities.com/tildemon.php