I drink a good amount of beer. Not as much as I used to (thanks marriage!) But I love beer-related trinkets, here are a few I've come across:
Local Brewery Tours
In most cities you can find local breweries that have tasting rooms or factory tours. They're always fun, you usually get a few drinks (and can usually try small batch brews), and they're likely free/cheap. Some larger cities have tours that hit multiple breweries if you poke around Yelp or Tripadvisor. I've been on amazing ones in Brooklyn, Milwaukee, and Boston.
Sam Adams Brewery Tour (Boston)
Drinking Jacket 2.0 by Zane Lamprey
Man, this is the ultimate tailgaters jacket. Has a zipper bottle opener, flask pocket, drinking mitts for when its cold, a koozie pocket, and a bunch of other random stuff.
Drinking Jacket 2.0 from Zane Lamprey
Industrial Growler - DrinkTanks Insulated Growler 64oz
Heavy duty growlers are popping up all over. Perfect for keeping your favorite local brew cold.
Wooden 6-Pack Holder
Etsy has a bunch of these. Pro move, add a mix-n-match 6-pack that your buddy will like.
Beer Cap Map
Great gift for the collector, Etsy has a bunch of options with different shapes for your local state.
YETI Hopper 20 Cooler
Pretty expensive at almost $300, but pretty practical. YETI's are known for amazing quality. They also offer some pretty cool stainless steel koozies if you don't want to spring for the full cooler.
Beer Cap Shadowbox from Craft Beer Hound
Another good move for the collector. Lots of options available, and there are some folks on Etsy selling these too.
Shadowbox Beercap Collector by Craft Beer Hound
Audacity of Hops Book
Drop a little knowledge on your bookworm beer buddy.
Already been said by others, but it is a great gift. There's something really satisfying about brewing (then waiting) and drinking your own beer.
Homebrew Kit from Amazon
Sorry, I had to. If you love your buddy and have a few (ok more than a few) bucks to throw around. The kegerator is the only way to fly.