I've been loving PostgreSQL's hstore ever since I found out about it. I frequently use it with Rails where I develop in a Vagrant instance. It's nice to be able to fully provision Vagrant instances to get them ready to use, and if you're using PostgreSQL and hstore, making sure hstore is enabled is part of that automation.
I got some help from StackOverflow in figuring it out, and I now have this Bash script that enables hstore if it isn't already enabled. It's included in this PostgreSQL chef-ubuntu cookbook that I contribute to, but it works just as well standalone or as an inline Vagrant provisioner.