I bought a Kershaw Whirlwind for about $55 last fall. It has spring assisted cam opening - which means it is about a close to being a switchblade as you can legally carry. It looks like a typical lock blade knife with a pocket clip and a nub on the blade for opening. The big difference is - when you start to push it open, all you have to do is get it started (maybe 1/6 open) and the spring takes over and flips it fully open. Its great fun. When I first got it, I could hardly stop playing with it (about drove my wife crazy for a few days). Anyway, it is a very solid, well-designed, well-made knife that can be very quickly and easily opened with one hand. If you try one, be careful not to let your thumb leave the handle when you flip it open or you could cut yourself. It feels a little dangerous at first, but after you practic a little, it becomes very natural. I really like this knife. There are more expensive versions and a few other variations. All are nice, but I think the basic whirlwind is a great buy.
Doug
Doug