I've seen this on twinks, +100 hp on helm. How is this done? Is it an armor kit made by a high-end leatherworker? Links would be appreciated. :)

As far as I know, its from a libram. You get a libram as a random drop, or off the AH, then get together some mats (usually from BRD, non bop), and turn in the mats with the libram and the turn in person gives you the enchant. They work on head and legs iirc.

Ok, thanks. Found the link: Libram of Constitution (http://wow.allakhazam.com/db/quest.html?wquest=4481)