Some rival services have domain managers where users can add a domain at no cost without help from an administrator, etc. Just by pointing DNS or cNames. Screenshots of their panels:

http://wimg.co.uk/TX7wvx.gif

http://wimg.co.uk/Rd4cat.gif

http://wimg.co.uk/4cne_g.gif

I'd love this option for vForums. :]