Good topic! I can't think of any of my close friends who do, sadly. I even gave one buddy a Vic Rambler keychain knife for Xmas a couple years ago so he'd stop mangling the lids on beer bottles and have a proper opener with him at all times. He was very gracious about the gift, seemed to really like it. But I've since noticed that it's not on his key chain and he still opens beer bottles like a caveman, prying them off (eventually) with whatever's at hand. :jerkit:
A few weeks back I was going with a friend to a govt. office to sign some paperwork for him as his witness. Going through security we had to empty pockets, of course. The security guard very courteously took my Buck 55 and gave me a receipt for to pick it up on my way out. As she was doing it, my pal, a guy I've known for YEARS, chuckles and says, "You carry a KNIFE!?" As if I were either A) some kind of hoodlum looking to stick a clerk in a liquor store of B) some whittlin' grampa from backwoods Kentucky. :jerkit: I just said, "Every day. Don't you?"
Also, a couple years ago my sister-in-law suggested my wife and I buy her husband a SAK for Christmas. I was jazzed to go knife shopping of course! I showed her my 84mm Tourist and she said it was EXACTLY what he wanted, something handy by not too big and not too small. So he opened it on Christmas and seemed to REALLY like it. Alas, it's been two+ years and I've never seen him carrying it.
My dad carries a SAK Classic on his keychain religiously and uses it all the time.