When you own a domain name (like blockland.us), you don't need to reserve subdomains. Otherwise I could buy "xxx.google.com" and charge Google hundreds of thousands of dollars if they ever wanted to buy it back. That's not how the Internet works.
forums.blockland.us exists for two reason:
1) The forums used to be hosted on PHPBB at forums.blockland.us, before some horrible error happened and Badspot migrated to SMF at forum.blockland.us.
2) For awhile after the move, the original PHPBB boards were kept up.
3) "forum.website.com" is more grammatically correct.
Also, Blocki has no idea what he's talking about. Subdomains can have subdomains.
