It's funny that I have carried the same Leatherman on my duty belt for 16 years, but I don't consider it a knife really. In my pants I carry a Spyderco Assist. I'm really digging it. It is very strange looking, but super comfortable in use. I used to carry a Benchmade 916, Triage. Sold it though. Never warmed up to the way the blade was ground. Always seemed twisted or bent.
In the car I carry a backpack/ bug out bag. It contains ammo, batteries, extra junk and my Swamp Rat Ratmandu. I can't really think of a time when I would need it at work, but I have it and LOVE the knife, so I like to have it with me. I'm waiting on a Mashed Cat Sheath for it.