Drupal extra subdomains for some special nodes
Have you looked at the Domain Access module?


  The Domain Access project is a suite of modules that provide tools for
  running a group of affiliated sites from one Drupal installation and a
  single shared database. The module allows you to share users, content,
  and configurations across a group of sites such as:
  
  
  example.com
  one.example.com
  two.example.com
  my.example.com
  thisexample.com &lt;-- can use any domain string
  example.com:3000 &lt;-- treats non-standard ports as unique
  
  
  By default, these sites share all tables in your Drupal installation.
  The Domain Prefix module (for Drupal 6) allows for selective, dynamic
  table prefixing for advanced users.


Basically you can assign a Node across any number of configured subdomains you've made drupal aware of.