It's been my personal experience that larger knives (With blades over 3 or 4 inches) are generally a waste, and just extra weight to carry around for the "LCF" (Though I'll forgive the venerable kukri right away, as I'm quite sure you could use it to chop down a tree in a pinch).
I've got to echo what somone else said about CRKT, fantastic knives... particularly anything in the M16 series... all quick one handed opening action... when I was buying, I needed somthing that could be opened while using my other hand to keep from falling off somthing... I chose it over a spring assisted smith and wesson knife, as the opening action was just as quick, but they're designed so they can be easily taken apart for cleaning and maintenence... I've got a M16 04Z and an M16 13SF (Bought cheap at a USAF BX) and I'm surprised Sig Des hasn't bragged about his, he's got a nice one...
If you buy one, go with the basic M16 series, my M16 04Z is a fantastic knife, fits perfectly into a spare gerber belt pouch I had. I found the "hilt" (They just widened the flipper, and added a mirror image of it on the opposite side) on the SF series (Particularly, my M16 13SF) were more in the way then anything, plus it was just a bit too long to fit in the same pouch as the other one. If you can find one for a decent price, I'm guessing the M16 titanium series would be better still.