I carry a Swiss Army Recruit knife. It rides in my pants pocket full time, whether I am backpacking, car camping, hiking, shopping for groceries, sitting in front of the computer... like I said: full time.

The Recruit model has: one large and one small blade, a can opener and a bottle opener (with large and small screwdriver blade tips), a toothpick, and tweezers. It weighs a bit more than 1.5 ounces (my cheap gram scale says 48 grams).

But knife preference varies widely and knife-using habits are equally individual, so what anyone else here uses will reflect their needs, habits and opinions, and may not fit your needs very well.