How is this done? Usergroup option on/off button of sorts.
 

This is a fantastic way to encourage subscriptions. The only thing I can find in their code is that it's commented with "VS_MOD Sidebar" but google tells me nothing.

This is from r6-forum.com. They have a sidebar on all pages, as well as IntelliTXT advertising. Once you purchase a subscription, the following shows up in your control panel:

http://www.metalguitarist.org/chris/vbo_options.jpg

I'm assuming it's come kind of combination of custom profile fields and template conditionals that are only available to the paid subscriber usergroup. Eg:

If usergroup=(subscribed) then (show the on/off buttons) in UserCP, along with if (usergroup=subscribed) then (parse the on/off selection) for the sidebar code and UserCP code.

It's excellent either way and I really want to go this route on my forums as well.