You can do this, but you'd need fields to manage that for each campaign.
Because of the way laws are written, you must unsub them from all emails if they request it.
The good news is you can create a subscription management center so you can keep people subscribed to what they do want, like Webinars, Events, Promos, etc. Do a search, there are tons of ideas.
Or see http://slideshare.net/jdavidhill