Look at the Benchmade Mini-Rukus.
Small, well, not exactly.
Light, well, no.
But it is razor sharp, holds an edge very well and is built like a tank. It also carries well, I carry mine daily and never notice it.

If you don't mind looking past a folder, BRKT (Bark River Knives) has knives in a wide range of sizes, including one that will fit in an Altoids size tin, for reasonable prices considering the high quality and very good customer service.

Looks like a good alternative. Found a nice price for it, too.

I just got some interesting feedback from the field in Iraq. Apparently the KA-BAR Desert Mule is winning over hearts and minds as a good utility/combat folder. It is a bit larger than your spec, but sounds like it is good and reliable. Not a bad set up for a $40 knife.

If the boys in the field are raving it, then it is worth further investigation I reckon. I do plan on getting one now. I am going to post this info in a new thread as well.

I am also going to check with the professional critics on Bladeforums and see what they say.

I am a bit of a Spyderco fan. I have a Spyderco Salt II in my pocket right now, but that might be a little small or light for the kinds of things you're talking about. The Spyderco Manix, which I have used but do not own, seems to be a very good knife indeed.

I personally put a Becker Necker in my larger survival kit instead of a folder. It's no longer in production and prices are climbing as a result, but it is small, light, extremely sturdy, and holds a very good edge. It has some additional functions - the handle has a cap lifter and a wire breaking notch in the butt. The skeleton handle also makes it easy to lash it to a pole for use as a spear.

"...lash it to a pole for use as a spear..."

Might be just me, but there is no way I would tie my only blade to a stick and throw it at something. Lots of bad things could happen. Instead, I would use it to sharpen the end of that stick, harden the end in a fire, and use that as a spear instead...

I wouldn't throw it either. It would be used to thrust the blade at something that was either too far away for me to reach or that I hope to keep far enough away to not reach me! For the most part, though, for gigging frogs and so on, I would prefer a sharpened stick, too.

The British Army Folding Locking Knife is useful available here



or the Fallkniven U2 folder.

My EDC knife usually rotates between a Spyderco Byrd series or a Opinel. I am not much into very expensive knives.

Recently, I have been carrying an EKA Compact. I like the Scandi grind. It is easy to sharpen and maintain. It has a large handle that feels good in the hand. It is not a locking blade though.

I have ordered a few more to go in my emergency kits and complement the fixed blade Moras in my car kits.

I like the Swiss Army Adventurer or the Hunter. They have locking main blades, some non-locking accessory blades that are handy ...are relatively small and are $22 or $27 from www.budk.com. Have also found them at www.knifecenter.com, though I haven't checked their prices recently.
The previously mentioned military knife is nice ...though not many other blades or uses....I prefer locking blades since folders that fold up when you use them only can contribute bad things to your survival situation. For small kits ...folder is best option for me ...bigger kits can have the fixed blade knives ...I like Ka-Bar ...decent price, good product, not a huge $$$ investment. Sometimes can find sales on para-cord wrappend handle blades for less that would work.
I also like the Leatherman Micra ...they are about $20 or so, but their blade is small...and I carry one all the tiem anyway ...so for a small kit something more is nice.
Love the Leatherman Wave also ... one in my kit in case I'm not carrying my other one...but they cost more (~$68) so to keep costs down my Adventurer is in my kits too.
I am leary of spending $100 or more for a blade I stash away for emergencies and don't use as its reserved for emergencies... that's a lot of $$ to tie up since all the other components cost real money too when you add it up. But that must be tempered with quality too.
One has to draw a line in the sand at some point.