I use IPv6, because I want to push forward this technology, because it's technologically superior and the address is shrinking very day. I heard that in Korea some people are NAT'ed twice. I want to avoid this in the future.
In similar respect, university accommodation here implements a 512k cap on internet speed for each student - however this is only for IPv4. With IPv6 I am reaching some high speeds over a Gigabit ethernet, plus the ability to host any sevices - as long as they are IPv6 :)
Additionally it's nice to be on a network that is underused. Especially, the advantages of multicast that IPv6 offers make an eventual changeover desirable (I run a student internet radio station, and hate the problem with unnecessary traffic).
However, I'm studying ipv6 for my thesis at the University of Padua. I am studying, in particular, the "ipv4 over ipv6"... I activated an IPv4 in IPv6 tunnel so that two hosts IPv4 only could connect each other through an IPv6-only structure.
This may be useful for companies with mixed connectivity.