Reputation on a site means you have reputation about that area, for example on SO that's typically programming, on SF that's System Engineer/Admin areas, etc. Being able to transfer rep would give an (IMO) undeserved weight to your content on a site, an area in which you've proven no expertise.
Privileges should be earned on that site I think...for example re-tagging, you should be around to know what the tags are, and for that matter what the topics are. Same goes for the ability to downvote, edit posts, close questions...you should have some expertise, as determined by the members of that site (e.g. your reputation earned) to have those rights.