Or you could burn the suggestions on here and add a few of your own - at least that way he might find something new that he likes and then checks them out under his own steam... that way you can try and mix Sunn o))), Isis and Mastodon with Sabbath,Led Zep, Monster Magnet, Fightstar,Kyuss, Fu Manchu, Slipknot, and also maybe some lighter stuff such as Shinedown, Secret Machines, Mark Lanegan (Hit The City), Foo Fighters, Jon Spencer Blues Explosion (Wail), Gallows etc,Maybe even some old old ACDC, Eagles of Death Metal (Boys Bad News)
Failing that get him some of the Desert sessions -
http://en.wikipedia.org/wiki/Desert_Sessions - which is an evolving band containing members of pretty much everyone above. My favourite is session 9 and 10, which has 'Make It Wi Chu' Whch is essentially Josh Holme and Ween
http://en.wikipedia.org/wiki/Volumes_9_&_10 . It also has the original version of 'In My Head' which was on 'Lullabies to Paralyze'
Or
Mondo Generator (Nick Olivieras band - he used to be in QOTSA)
Masters of Reality
Or
Have a look at this -
http://www.last.fm/music/Queens+of+the+Stone+Age/+similar