I was thinking about this the other day. I have so many I've lost count. I know the mini-tools are the best bet because of their versatality, but sometimes just a little quality knife does the job, (I know, I LOVE scissors too). I have a little Spyderco, (I believe made by Moki), that has a miniature red light built into it, that is a handy little sucker. I also have just recently received a Reeve Umfaan that is classy as hell, is tiny, (with a surprisingly big blade for it's size), but at $280.00 a pop, is too impractical to carry on a keychain, (though you could if you were Mike Turber). I also have one of the CRK&T's K.I.S.S. knives, but in my estimation it is slightly too large for keychain duty. For me the nod goes to the Al Mar Micro-Sere. A great little knife, that is tiny, quality, and really will do big jobs if need be. I know the steel is only AUS-6, but for the small amount of jobs it does, it is fine. And this knife like most Al Mar's, exudes quality, (smooth opener and classy slotted aluminum scales), and is fairly reasonable, (around $40.00, if you consider that reasonable for a KC knife). What's yours?