I've got a Husky utility knife that I use when I don't want to muck up my other knives. It's got thumbstuds, but the backspring (or whatever's holding it closed) puts enough pressure on it that I can't open it one-handed, so it's not likely to swing open like the Superknife Doughnut described. Someone with larger/stronger hands than mine could probably open it one-handed, though.