I love the Simon and Garfunkel idea- don't know how old you are though, lol!
And actually I bought my ex a gorgeous locally-blown water pipe for our first Christmas together. He loved it. Too bad he's an ass. lol.
Extravagant coffee-table books are great too for the stoner in your life. There's nothing like snuggling on the sofa on a cold winter day, getting baked, and looking at amazing photography or art. Some of my favorite subjects are garden design, travel, castles and villas, and FOOD (duh... lol for anyone who knows me that's a no-brainer). If you see yourselves together for a significant length of time and intend to travel, books about exotic destinations are a GREAT gift. Find out where he's always wanted to go.
I gotta say on behalf of the site, sorry about that mess in that welcome thread that got locked; really this place is a lot more chilled than you might have been led to believe.