I've seen some people on here have like a set of signatures that rotate for each post. How do they do that? I want to be able to do that...

google "sig rotator"

should be the first result

enter name and password

enter your links for sigs

it will give you a universal link that you use as your sig and it will rotate the links you supply

thanks, I actually found one minutes after posting lol.

http://sig.grumpybumpers.com/