Signature Switch
 

On Yuku, usernames are allowed to have up to five different signatures that they can switch between while posting, or 10 if their account is Supporter status. I am moving my forum over from Yuku to vBulletin, and my members desperately want this feature to stay. I admit that I don't know how difficult it would be to achieve something like this, but I would really appreciate it if someone could make me a mod that allows a user to add as many new signatures as they want to, set a default signature, but be able to choose which one to use when they post.