domains and sun-domains

[Ninth Dimension]

I'm looking for a hack that will allow my users to be logged in, regardless of which domain or sub-domain they are using to access the site.

let me go into some more detail:

I'm setting up a network os sites, using vB as the backbone of the network so far as members are concerned, this site is going to be split accross several domains/sub-domains, based on which section of the network they are visiting.

e.g.
ofdan.net - main ntwork page
eerie.net - paranormal section
writeoutthere.com - interactive story
forums.ofdan.net - forums
etc...

Now on some of the sections, users will be able to submit there own comments/content, but only if they are logged in.

(are you still with me? )

I would like to be able to keep the session/cookie data set by vB to the users browsers, and give my scripts access to it, regardless of which domain they are using to view the scripts.

I hope you know what I mean, and I also hope that someone might be able to point me in the right direction with regards to solving this problem.

cheers