Not your standard Ka-Bar, but I've been carrying the Ka-Bar TDI design by John Benner for 6 months now and I love it. It's not your standard fixed blade, it's a karambit style, but it's incredibly fast to employ from your belt or from concealment with either hand.
They make them in several makes and models.
Serrated...
Longer...
Tanto...
Last Ditch...
I really can't recommend this knife highly enough. I carry it along with my Leatherman and a titanium Boker Magnum. The others are my work knives, the TDI is my "in case" knife.
To give you some perspective on what a little training will accomplish; I had an uncle stand about 12 feet in front of me with 9" diameter rubber ball. He then threw "lobbed" the ball at me over-handed. My TDI was on my left hip under a t-shirt and sweatshirt, and from concealment I was able to deploy it with my right hand and pop the ball before it hit me. Think about it.
~LT
Oh, and it retails for around $35.