Add dtdns.com ?
Is it possibel to implement dtdns.net ?
also would be nice to have multiple dyndns clients for different sites.
Yes its possible. The entire dynamic dns client is written in PHP so its easy to extend.
However, I have no immediate plans on adding any new providers… I welcome someone else in the community to do it.
If this is something you really want you may want to post a bounty and see if another developer bites.