captain universe is a character/power that inhabits other people in certain times of need. captain universe is incredibly powerful. he's pretty much one of those "can almost do anything" type of guys. there was a story back in the day (back when mcfarlane was still drawing spidey) where spidey was given the power of captain universe, but due to interference, ONLY got the powers, and not the knowledge of who and what captain universe is and what his mission is with those powers (which are usually part of the package).
i'm not sure if it's still in print, but if you search the intraweb for the "cosmic spider-man" trade paper back, you might be able to find it. i'd suggest picking it up. it's actually a pretty decent story.